A corruption scandal has shaken the European Parliament as Belgian police arrested a vice president of the institution and carried out multiple searches at the parliament, and in private residences.
Here's what we know so far about the scandal that was first revealed on Friday evening.
What do we know about the alleged corruption scandal at the European Parliament?
At least six individuals have been arrested by Belgian police following a "major investigation" into corruption, money laundering and criminal organisation.
Two of them have been released with or without conditions, according to the Belgian federal prosecutor's office.
One of the individuals is Eva Kaili, a Greek MEP who until Tuesday was one of 14 vice presidents of the European Parliament.
She is suspected of lobbying on behalf of a Gulf country, which was identified by media and some MEPs as Qatar, the host country of the 2022 FIFA World Cup football tournament.
The Qatari government denies involvement and the Belgian prosecutor's office would not confirm the country's name.
She has been reportedly arrested despite her parliamentary immunity, something that is only possible when an MEP is "found in the act of committing an offence", according to the EU parliament's website.
The Belgian federal prosecutor's office said in a statement on Monday that at least 20 searches were carried out in total -- 19 in private homes and one in the offices of the parliament.
They seized several hundred thousand euros in three separate locations: "600,000 euros at the home of a suspect, several hundred thousand euros in a suitcase in a Brussels hotel room and about 150,000 euros in a flat belonging to a Member of the European Parliament."
European Parliament President Roberta Metsola said that she accompanied a Belgian judge and police to a house search over the weekend, as required by the country's constitution.
Belgian newspaper Le Soir reported that Kaili's partner Francesco Giorgi and former MEP Pier Antonio Panzeri were also arrested.
Ten parliamentary staff had their IT resources frozen since Friday to "prevent the disappearance of data necessary for the investigation," the federal prosecutor's office added. Police searches have also been carried out in Italy, it said.
The suspects are expected to appear before a pre-trial court on Wednesday.
What has been the reaction in the European institutions?
European lawmakers voted on Tuesday to strip Eva Kaili of her position as vice president in the European Parliament with 625 voting in favour, one against and two abstentions.
Metsola had strong words on Monday, warning that there would be "no impunity" for members found guilty of corruption.
"Make no mistake. The European Parliament, dear colleagues, is under attack. European democracy is under attack. And our way of open, free, democratic societies are under attack," Metsola said.
"Corruption cannot pay and we have played our part in ensuring these plans could not materialise."
European Commission President Ursula von der Leyen said that the "allegations against the vice president of the European Parliament are of utmost concern, very serious."
"It is a question of confidence of people into our institutions and this confidence and trust into our institutions needs higher standards of independence and integrity," she added, talking about creating a new independent ethics body.
What has happened to the Socialists & Democrats?
The investigation has impacted a number of lawmakers associated with the Socialists and Democrats group in the parliament.
Eva Kaili was suspended from the Socialists and Democrats group on Friday as it emerged that she had been arrested.
The chair of the group in parliament, Iratxe García Pérez, said that the group was shocked by the scandal.
"Today is a dark day for the European institutions and of course for the European Parliament and for our political family," she told reporters.
She said that lawmakers affected by the investigation or linked to parliamentary assistants involved would be temporarily suspended.
García Pérez added that Qatari authorities should also collaborate in the investigation and that if it is proven that they tried to undermine European democracy, there should be sanctions.
The group told Euronews that MEP Marc Tarabella suspended himself, Pietro Bartolo stepped down as shadow rapporteur for the LIBE committee file on visa liberalisation, and Andrea Cozzolino stepped down as S&D coordinator of urgencies.
Belgian Socialist MEP Maria Arena said on Twitter that she would no longer chair meetings of the human rights sub-committee due to the search of one of her assistants in the case.
What have the MEPs caught up in the case said about Qatar?
Kaili's relations with Qatar are gaining new meaning amid the corruption scandal, with many reposting a speech she gave in the Parliament praising the World Cup hosts.
"Today the World Cup in Qatar is proof actually of how sports diplomacy can achieve a historical transformation of a country with reforms that inspired the Arab world," she said.
She said Qatar was a frontrunner in labour rights and that some members of the European Parliament were discriminating against the country and bullying them.
"(MEPs) accuse anyone that talks to them or engages (with them) of corruption," she added.
MEP Marc Tarabella had also previously defended Qatar's labour reforms, stating it was "still the country that has embarked on the path of reform."
Tarabella and Kaili, along with Bartolo voted in committee in favour of no longer requiring visas for Qatar and Kuwait citizens.
What attention has this scandal brought to ethics in the European Union?
The scandal has put EU ethics rules and lobbying in the spotlight, with European Commission President Ursula von der Leyen saying that there was a need for "higher standards".
Von der Leyen said that she sent a letter about an independent EU ethics body that should be established for all institutions.
"For us, it is very critical to have not only strong rules but the same rules also covering all the European institutions and not to allow for any kind of exemptions," von der Leyen said.
Transparency International EU's deputy director Nicholas Aiossa said that the organisation had been calling for an ethics body for "many, many years" but that there is a "general lack of political will" to create one.
"What needs to happen is that the European Parliament should take swift action in the interim to address some of the corruption risks and ethics risks that presently exist within their power to do so," Aiossa told Euronews, adding that there were a number of reforms that could be taken without the Commission proposal.
The organisation has more specifically called for the European Parliament's "ruling Bureau", which is made up of the president, 14 vice presidents as well as administrative and financial personnel, to "be stripped of all decision-making powers when it comes to issues of ethics, transparency and integrity."
They also called for the MEP code of conduct to be revised and for third-country governments who lobby institutions to be included in the transparency register.
"I think that the events that have unfolded in the last four days should serve as a wake-up call for the Parliament especially, to try and root out what we feel is a culture of impunity that has been left to fester for many, many years when it comes to ethics and anti-fraud measures in the house," said Aiossa.
What happens next?
Four of the individuals who were arrested will appear in court on Wednesday as part of a pre-trial hearing, the Belgian Federal Prosecutor's office confirmed to Euronews.
There it will be decided whether they will stay in jail or be released before a trial.
Organisations working on corruption issues say that the European Parliament needs to raise its standards and make urgent reforms to its rules.
Olivier Hoedeman at Corporate Europe Observatory, an organisation that works to expose corporate lobbying, said that the European Parliament is "definitely very vulnerable to this kind of scandal by choosing to not tighten the rules to the extent that they need to."
"I think it's really crucial that the leadership of the European Parliament gives the signal that they will now embrace a far stricter approach towards lobbying and influencing actions across the board because, because this scandal has highlighted that the approach of the European Parliament is just far too weak," he said.
He said it would be tragic if there wasn't movement on the issue.
"They need to raise the standards on whistleblower protection when it comes to EU staff, which are very subpar," said Aiossa.
"They need to clean up the self-policing system they have in place when it comes to ethics and their own members of the European Parliament.
"They need to have a sanctions regime in place for violations that actually serve as a deterrent, which they don't presently have. There's a host of reforms that should be brought into force."