The two men will debate Europe and Mr Blair may get clear backing from Mr Sarkozy in exchange of his participation at the conference, according to media reports.

The UMP meeting marks the launch of its pre-electoral campaign before the municipal elections in France on 9 and 16 March – but there is set to be much speculation around Mr Blair's attendance.

The president of the socialist group in the French national assembly, Jean-Marc Ayrault, has accused Mr Sarkozy of preparing the ground for Mr Blair's candidacy for the EU top job with Saturday's event.

"I see something emerging from the UMP's side and from the president of the republic (…), which is preparing Tony Blair's candidacy for EU president", Mr Ayrault was reported as saying by French news agency AFP on Tuesday (8 January).

"This candidacy is not acceptable, because it is not acceptable that the first EU president is a man who supported and participated in the war in Iraq", he added.

Other politicians who have already expressed interest in what is to set to be one of the EU's top jobs include Luxembourg's prime minister Jean-Claude Juncker and his Irish counterpart Bertie Ahern.

Two more positions are also up for grabs next year – president of the European Commission and EU foreign minister.

Haggling over the nominations for the post is set to start in earnest in the second half of this year when France takes over the EU presidency.