A Belgian member of the European Parliament linked to the corruption scandal that rocked the bloc in December was detained for questioning on Friday.
Belgian police conducted a series of raids across the country, the federal prosecutor’s office said.
Prosecutors referred to the EU MEP only as MT, but a source close to the case confirmed that Marc Tarabella, 59, had been detained early on Friday.
Four others, including Greek MEP Eva Kaili, are already in custody in Belgium facing charges of corruption and money laundering in relation to alleged payments from Qatar and Morocco. Both countries deny involvement.
Several raids on Friday morning targeted Mr Tarabella, including offices in Liege and the town hall of Anthisnes, where he is mayor.
Mr Tarabella was “detained for questioning” and the judge overseeing the case will decide in the coming hours whether he should appear before him, prosecutors said.
The European Parliament last week voted to lift his immunity from prosecution, and that of Italian fellow MEP Andrea Cozzolino, after a request by Belgian investigators.
Both have insisted they are innocent and Mr Tarabella has said he was looking forward to the chance to clear his name.
The scandal centres on allegations that Qatari and Moroccan officials offerd bribes to influence decisions at the European Parliament.
According to the report compiled to lift Mr Taraballa’s immunity, a Belgian investigation showed that he “may have been involved in acts of corruption connected with interference by one or more foreign states aimed at influencing the debates and decisions taken in the European Parliament”.
It said “testimony against him suggests that such payments were made to him on several occasions, amounting to a total of between ”€120,000 and €140,000 ($132,00 and $154,000).
Ms Kaili was one of the parliament's 14 vice presidents although she has since been stripped of that position.
The others detained are her boyfriend, Francesco Giorgi, former MEP Pier Antonio Panzeri, and Niccolo Figa-Talamanca, head of a charity group.
Mr Panzeri cut a deal with prosecutors last month in return for a lighter sentence, promising to reveal details of who was being bribed.