Belgian prosecutors on Wednesday charged Italian European Parliament member Andrea Cozzolino with corruption and money laundering in a high-profile graft scandal. 

The socialist MEP, 60, flew into Belgium on Monday for questioning after being arrested four months ago in Italy on an international warrant. 

Cozzolino, who denies any wrongdoing, is the third lawmaker to be charged over an alleged bribery scheme involving Qatar and Morocco aimed at swaying the European Parliament. 

He was released under supervision after being charged with "public corruption, (involvement in a) criminal organisation and money laundering", Belgium's federal prosecutor said. 

The Qatargate corruption scandal has rocked the European Parliament and pushed EU institutions to speed up reforms aimed at curbing outside influence.

It erupted in December when Belgian police detained several political figures and uncovered over 1.5 million euros ($1.6 million) in cash during a string of raids. 

Both Qatar and Morocco deny involvement in any corruption. 

The Belgian investigation was buffeted Monday by a decision to replace a key judge overseeing the case for a potential conflict of interest. 

Belgian media reported Michel Claise stepped down due to business links between his son and the son of an MEP whose name has figured in the probe. 

The federal prosecutor has said it expects the investigation to be completed by the end of the year.