LONDON, May 25 (AFP) - A new biography on Marshall Philippe Petain says the head of the World War II French collaborationist government may have tried to surrender to the British in 1943, only to be flatly rejected.   

Author and historian Charles Williams says that newly discovered "top secret" documents in the British national archives show that Petain proposed to leave Vichy and sign a peace agreement with the free French government based in Algiers.  

The offer, which never even made it to the desk of Prime Minister Winston Churchill, was apparently brushed aside by Harold Macmillan, a young British minister who later became prime minister and was working at the time at allied headquarters in the Mediterranean.   

"Petain seemed ready to go anywhere except north Africa," says the new biography, "making it known that if he left France the French army would be released of any allegiance to him."    

The "Victor of Verdun" made contact with the British with the help of a mysterious go-between known as "Monsieur Schneider."  

While it was not the first time Petain would approach the British in 1943, it was apparently the only time he offered to surrender.