The British Prime Minister, David Cameron, is fond of telling a story that he was apparently once approached to become a Cold War Russian spy during his gap-year travels in the Soviet Union.

But, in a somewhat obvious snub, a Russian author and intelligence historian has dismissed Cameron's story, instead claiming that the "agents" trying to recruit him were salesmen, adding that it was more likely to be a "gay pickup."

Speaking to Russian newspaper Komsomolskaya Pravda yesterday, Gennady Sokolov said high-level KGB agents had informed him Cameron was never approached to be a spy.

The prime minister has claimed to have met two Russians on a beach usually reserved for foreign tourists on the Black Sea coast.

In a speech at Moscow State University in 2011, Cameron said: "They took me out to lunch and dinner and asked me about life in England and what I thought about politics. When I got back I told my tutor at university and he asked me whether it was an interview. If it was, it seems I didn't get the job."

On the BBC's Desert Island Discs he added the pair were "obviously very careful and guarded in what we said, but later on when I got to university my politics tutor said that was a definite attempt at recruitment."

He also recounted the tale to former Russian President Dmitry Medvedev, who responded by saying: "I'm pretty sure that David would have been a very good KGB agent. But in this case he would never have become prime minister of the UK."

But Sokolov dismissed the claims, saying that "if the KGB had a task to work with a 19-year-old unknown young man Cameron, there would have remained certain paperwork on this matter."

"We have cautiously asked well-informed people if there is a file on Cameron in KGB archives," he said. "We got a definite reply that there is no such file in the archives, and there was no such file earlier. The KGB was not working on Cameron."

Sokolov added: "The pair planned to buy some foreign stuff like jeans to resell them later and, after all, to make friends with two nice looking British guys — there was also a gay motive."

The comments came as Cameron accused Russia of "standing in the way of justice" after it vetoed an United Nations Security Council resolution that aimed to establish an international tribunal with powers to prosecute those responsible for the downing of Malaysian Airlines flight MH17 over eastern Ukraine last year.

Eleven Council members, including permanent members France, the UK, and the United States, voted in favor of the resolution on Wednesday. Russia was the sole vote against the text, while three countries — China, Angola, and Venezuela — abstained.

Cameron responded by saying the move was "infuriating and completely wrong."

"Let us not forget: British people died on this flight. Hundreds of people died on this flight. We cannot let one country stand in the way of getting to the truth or one country stand in the way of getting justice," he said.

"If we cannot set up a tribunal through the United Nations route, we will have to look at other ways to make sure this is done. As in the case of the Lockerbie disaster, justice must be done."