Top British military chiefs secretly approved plans to arm the Vichy French regime during World War II − and kept Winston Churchill and Charles de Gaulle in the dark about the plot.

Newly-unveiled documents show hushed-up negotiations led to a May 1942 plan to arm the supposedly neutral Vichy regime, which was collaborating with Nazi Germany, even though Britain was fighting Vichy troops in Madagascar at the time, claimed the BBC.

Neither British Prime Minister Churchill nor De Gaulle, the leader of the free French forces, knew anything about the proposal.

The plan was quietly dropped by November 1942, when the lack of Vichy resistance to the allied invasions of French North Africa − which prompted the Nazi occupation of Vichy France − killed it off completely.

Historian professor Eric Grove discovered the documents.

“Having been fighting the Vichy French in Syria in 1941, and indeed, in May 1942, we were actually fighting Vichy forces in Madagascar, and here we are talking about arming their colleagues in France itself,” he told BBC radio.

In December 1941, an officer of the third bureau of the French general staff at Vichy arrived in Britain for a meeting with a representative of the general staff in London.

“They wanted us to arm eight French divisions to take part in the liberation of France,” Prof. Grove said.

The talks led to a secret plan, approved in May 1942, which involved allied forces landing at occupied Bordeaux and La Rochelle on France’s west coast, before securing a corridor through to unoccupied Vichy France, with the help of Vichy forces.

The plan had the backing of the Vichy chief of the general staff and was approved by General Alan Brooke, the head of the British army.

It seems Churchill and De Gaulle were not told about the plan due to worries about how they might react, the BBC said. Both leaders had made clear their contempt for the Vichy regime. War historian Max Hastings said it was “amazing” that the chiefs of staff committed to paper the fact that it was not to be mentioned to Churchill. If Churchill had known, “Brooke would have had a very, very bad half-hour indeed with the Prime Minister”, Mr Hastings said.