Stalin, Churchill broke the ice in heavy-drinking session

Soviet dictator Josef Stalin and Britain's wartime prime minister Winston Churchill enjoyed an alcohol-fuelled all-nighter in Moscow as the second world war was in full swing, previously secret files have revealed.

Relations between the two leaders were described as "stiff" until Churchill arranged a tête-à-tête with Stalin, with the aid of interpreters, which led to a late-night, boozy banquet in 1942, according to files released by Britain's National Archives.

"There I found Stalin and Churchill, and Molotov who joined them, sitting with a heavily laden board between them: food of all kinds, crowned by a suckling pig and innumerable bottles," wrote Sir Alexander Cadogan, permanent undersecretary at the Foreign Office, of the visit.

The mood was as "merry as a marriage-bell", he added, though Churchill was complaining of a "slight headache" when Cadogan came to find him at one in the morning and "seemed wisely confining himself to a comparatively innocuous effervescent Caucasian red wine".

The two leaders did not engage in much military talk during the meeting, which went on until three in the morning, but Churchill did probe the Georgian-born dictator about his internal policy.

Asked what was happening with the kulaks, the relatively rich farming class Stalin had vowed to exterminate, he responded "with great frankness" saying that the kulaks had been given land in Siberia, but "'were very unpopular with the rest of the people!'"

The evening was dubbed a success by the author of the note, as the two men had got on.

"Certainly Winston was impressed, and I think the feeling was reciprocated," Cadogan reflected in his notes.