Since being defeated by Hollande last May -- and vowing never to return to politics -- Sarkozy has kept a low profile, working at his law firm in central Paris.
Mr Prodi, who defeated Mr Berlusconi in a general election seven years ago, could well return to Italy in 2004 to lead the opposition into the next one.
The government has been defeated in the Lords over plans to allow employees to give up workplace rights in return for shares in the company they work for.