Lawyers for Dominique Strauss-Kahn have proof the IMF chief was at a restaurant having lunch with his daughter at the time he was alleged to be sexually assaulting a hotel maid, France's RMC radio reported on Monday.

RMC said the lawyers had pieced together Strauss-Kahn's movements and found that he left the hotel at midday, after paying his bill and handing in his key, then went to eat with his daughter and took a taxi to the airport.

The schedule meant he had already left the hotel at the time the maid alleged he chased her down a corridor, forced her into a room and assaulted her, RMC reported on its website, adding that the lawyers had material evidence and witnesses.

Strauss-Kahn, a centre-left former finance minister whom polls had tipped as the likely frontrunner to win France's 2012 presidential election, will appear in court on Monday. The case has sent shockwaves around the world.

His lawyers have said he will plead not guilty to charges of a criminal sexual act, unlawful imprisonment and attempted rape, which threaten to bring a humiliating end to his career as International Monetary Fund managing director.

The radio did not cite its sources.