The Greek MEP will appear before a judge in Brussels on Thursday.
The lawyer of MEP Eva Kaili on Wednesday claimed her innocence in the so-called Qatargate corruption case that has shaken the European Parliament.
Michalis Dimitrakopoulos spoke to Euronews after meeting the former parliament vice-president for more than four hours in the Belgian prison where she's been detained since her arrest, to prepare for a pre-trial hearing on Thursday.
"The criminal procedure is secret. For this I can't say much, but the only thing I can say is that Eva Kaili is innocent," Dimitrakopoulos said.
Kaili, he added, feels betrayed by her partner, Francesco Giorgi, who has also been arrested in relation to the scandal.
"She feels betrayed by her partner. She trusted him and he betrayed her," Dimitrakopoulos said.
Kaili and her partner are both accused of corruption, money laundering and participation in a criminal organisation to lobby in favour of countries, alleged to be Qatar and Morrocco.
The judge must decide if she will remain in jail or if she will be freed with restrictions until a possible trial begins.
Last week, a Brussel court confirmed the pre-trial detention of Giorgi and former Italian MEP Pier Antonio Panzeri, while Niccolò Figà-Talamanca, secretary-general of No Peace Without Justice, "remains in custody but under the terms of the electronic bracelet."
Dimitrakopoulos told Euronews that "we have strong legal arguments for her release."
"We will fight because I believe that Ms. Kali is neither a flight risk, nor is there any way she can destroy evidence."
According to Belgian newspaper Le Soir, Kaili has partially recognised her involvement in the scandal, since she admits asking her father to help hide the money.
The lawyer denies the validity of this information.