The European Parliament's second largest political group demanded that the "wise persons" should be made up exclusively of judges, official auditors or prosecuting magistrates with a track record in fraud investigation.
The committee of inquiry is the centrepiece of a compromise deal struck last week in Strasbourg after a clash between the Parliament and the European Commission over fraud allegations.
A dispute over its composition could delay the process of setting it up and derail its tight timetable, destabilising the fragile agreement.
The manoeuvring followed speculation about the composition of the committee, due to inquire into irregularities in programmes presided over by two European commissioners, Edith Cresson and Manuel Marin, and produce a preliminary report by 15 March.
Potential nominees being discussed among socialist MEPs and in the Commission include the former European commissioners Etienne Davignon and Peter Sutherland, and two figures involved in the preparation for monetary union: Nigel Wicks, the former chairman of the monetary committee, and Alexander Lamfalussy, who presided over the European Monetary Institute.
Although confusion surrounds the procedures for appointing the committee, Commission sources said they expect two members to be nominated by them, two by the Parliament, and a chair appointed by mutual agreement.
It emerged, however, that centre-right MEPs may demand the right for Parliament to appoint all the members - a move one political rival described as an attempt to "sabotage" the process.
James Provan, chief whip for the European People's Party, the Parliament's second largest grouping, said the idea of ex-commissioners sitting in judgement was "completely unsupportable". He added: "They must have nothing to do with the institution concerned. Whoever is appointed must be seen to be independent and fair-minded. This would include judges and members of the Court of Auditors."
James Elles, the party's representative on the Parliament's budget control committee, said: "You do not normally give the body you are inquiring into the right to nominate those doing the investigation.
"The membership will have to be approved by Parliament on 8 February. To then expect their report to be available in 11 languages by 15 March is laughable."
Other political groups in the Parliament, including the Greens and the Liberal Democrats, are on record as being highly critical of the investigation procedure.Reuse content