Romania asks to lift immunity of cash-for-ammendments MEP

Unlike two other MEPs from Slovenia and Austria, Zoran Thaler and Ernst Strasser, who promptly resigned from the Parliament after being exposed by the Sunday Times sting, Severin has refused to end step down, despite being expelled from the Socialist group and facing open booing from his colleagues.

A fourth MEP, Pablo Zalba Bidegain from Spain, is also keeping his job for now, as he claims he only talked to the alleged lobbyists, but never actually accepted their offer.

Severin, a former foreign minister in post-Communist Romania, denies any wrongdoing. During his five years as an MEP, Severin has always tried to downplay Romania's corruption problem and portray those who criticise it as the country's detractors.

Wary that Romanian anti-corruption inquiries take too long and get bogged down in courts by judges unwilling to go after high-ranking politicians, a series of campaigners have meanwhile asked the Belgian authorities to take over the case, as the deeds were committed in Brussels.

Friends of the Earth Europe and Transparency International in recent days repeated calls for the Belgian public prosecutor, Johan Delmulle, to start an official investigation.

EU's anti-fraud office Olaf is already carrying out an investigation into the matter but it relies on national authorities to take the cases to court.

"The four parliamentarians seem to be involved in corruption, which is a serious crime. This should be investigated swiftly and thoroughly and if they are found guilty there should be strong penalties. The Belgian government is best placed to ensure that all four MEPs are treated the same," Paul de Clerck from Friends of the Earth Europe said.

The European Parliament itself is currently reviewing its code of conduct. In a press conference on Tuesday, Socialist leader Martin Schulz repeated calls for Severin to "give back his mandate," and said that MEPs should not have other paid jobs on the side.

"Being an MEP is a time-consuming job and a well-paid one. Parliament has to make sure that members cannot use their position as an MEP to make money on the side," he said.

A seven-point plan intended to tackle the issue was presented last week by parliament chief Jerzy Buzek and is currently being negotiated with group leaders.

But anti-corruption campaigners warned of this "not to become a tick-box exercise".

"There is a role for civil society to verify that the changes are meaningful and lasting. Transparency International will rigorously monitor the process to ensure a true "zero tolerance" approach to corruption," Jana Mittermaier from the TI's Brussels office said in a statement.