Police on Friday detained a Belgian European Parliament member for questioning after searching a bank safe belonging to him as part of a probe into a bribery scandal that has rocked the EU.

Belgium's federal prosecutors said "several raids" were carried out Friday morning targeting the safe of lawmaker Marc Tarabella, 59, in the city of Liege and offices in the town hall of Anthisnes, where he is mayor.

Tarabella was "detained for questioning" and the judge overseeing the case will decide in the coming hours whether the Socialist MEP should appear before him, prosecutors said.

The parliament last week voted to lift Tarabella's immunity from prosecution, and that of Italian fellow MEP Andrea Cozzolino, following a request by Belgian investigators.

Both have insisted they are innocent and Tarabella has said he was looking forward to the chance to clear his name.

Belgium authorities already have three suspects in custody after launching raids on several addresses in December -- including those of lawmakers, ex-lawmakers and parliamentary aides -- that turned up 1.5 million euros ($1.6 million in cash).

Those detained, and charged with corruption, money laundering and criminal organisation, include a Greek MEP Eva Kaili, who was one of the parliament's 14 vice presidents but who has since been stripped of that position.

The other two are: her boyfriend, Francesco Giorgi, who was a parliamentary aide, and former MEP Pier Antonio Panzeri, who founded an NGO that dealt with the parliament.

Panzeri cut a deal with prosecutors last month in return for a lighter sentence, promising to spill the beans on the countries that gave the alleged bribes and people he paid off.

Belgian media has reported that Panzeri told investigators he gave Tarabella "between 120,000 and 140,000 euros" for his aid in handling matters linked to Gulf state Qatar.

The authorities in Qatar and Morocco have denied any involvement in the case.

The so-called Qatargate scandal has sent shockwaves through the EU's institutions and caused the parliament to hastily seek reforms looking to curb outside influence.