The suicide of Joseph Stalin's eldest son in a German concentration camp has been disclosed in full detail by official documents just made public, according to the Sunday Times of London.

Jakov Stalin's death in Sacsenhausen concentration camp in 1943 remained a mystery for years and at one stage his father offered a 1 million-ruble reward to anyone who could find the grave.

But the newspaper said in a story for its Sunday editions that British and American authorities had known all along about Jakov.

It said the full facts, describing how Jakov ran to the camp's electrified fence and taunted a guard into shooting him, were kept secret to avoid upsetting Anglo-Soviet relations.

Captured German documents, just made public by the British Foreign Office, show that British and Soviet prisoners in the camp had been arguing constantly.

The newspaper said that according to the documents it had scrutinized, Stalin's son -- who had been an artillery commander on the German front -- became particularly provocative.

On April 14, 1943, there was a violent argument ending in a fight in the camp. When Jakov's request to see the camp commandant was turned down, he appeared to go berserk, the Sunday Times said.