"The visit is connected to an ongoing inquiry in Thuringia, Germany," an EPP spokesperson said in a press release provided to Euronews.
Police from Belgium and Germany raided the offices of the centre-right European People's Party (EPP) in Brussels on Tuesday morning.
The EPP is the largest party at the European level and its group holds the biggest number of seats in the European Parliament.
Its headquarters is located in Rue du Commerce, in the European quarter of Brussels.
"The visit is connected to an ongoing inquiry in Thuringia, Germany," an EPP spokesperson said in a short press release.
"The party is cooperating in full transparency with the authorities involved, providing all relevant information and documentation."
The party did not provide any further details about the investigation.
The Thuringian authorities did not immediately reply to a request for comment.
German media reported the probe is not directed against the party or any of its current employees but against Mario Voigt, the CDU leader in Thuringia, who is suspected of corruption and bribery.
Voigt worked for the EPP during the 2019 electoral cycle.
Investigators are reportedly trying to determine how much money Voigt possibly could have received or handled during that time. They are also searching for documents regarding work contracts and speaking with witnesses in Brussels, German media said.
Voigt denies the accusations. His lawyers have described the probe, which began in September 2022, as "disproportionate and excessive" and insist his client has done "nothing wrong."
A pan-European group, the EPP encompasses some of Europe's most prominent politicians, including European Commission President Ursula von der Leyen, European Parliament President Roberta Metsola, Greek Prime Minister Kyriakos Mitsotakis and Swedish Prime Minister Ulf Kristersson.
The EPP is currently led by Manfred Weber, who hails from the Bavaria-based CSU party.
This article has been updated to include new information.