A dozen Romanian anti-graft groups on Wednesday asked the European Parliament and several private and public institutions not to cooperate with a Romanian European lawmaker accused of corruption.

"We believe the presence of Adrian Severin in the European Parliament is seriously damaging the image of this institution," the non-governmental organisations wrote in an open letter to the European legislature.

"Moreover, the fact that Adrian Severin holds positions in managerial as well as consultative bodies of public and private institutions (in other European countries) is damaging the credibility of these institutions," they added.

The NGOs who operate through the anti-corruption platform "For a clean Romania" sent the letter to the Chamber of Commerce and Industry of Slovenia, Malta and Romania as well as to the International Chamber of Commerce in Paris and the Italian Unicredit bank.

Three lawmakers from Austria, Romania and Slovenia are under investigation at home and in Brussels after a sting by Britain's Sunday Times newspaper reportedly showed them agreeing to take bribes of up to 100,000 euros ($140,000).

Austrian MEP Ernst Strasser and Slovenian Zoran Thaler resigned but Severin so far has refused to do so, denying having committed any illegal act.

His refusal to resign has stirred uproar in Romania.