A Chinese agent, who reportedly posed as an official interpreter, attempted to get inside the carriage with Queen Elizabeth and her guests during Xi Jingping's official state visit. The attempted security breach that took place on 20 October, has led to a tense stand-off between security services of the two countries.

"The bodyguard, or spy, attempted to get in the carriage and was prevented when it was ascertained by our security officials that he was actually a security official rather than the official translator," a British official told The Sunday Times.

The British diplomatic protection squad intercepted the Chinese official and he was immediately ousted according to documents circulating in Whitehall. A royal source, however, said, "No one got into the carriage except the principals."

Details of the spat emerged amid concerns that the security services were too quick to do China's bidding during the state visit. "There was a stand-off and our protection people were shouldered aside. There's an issue here about bullying, uncomprehending Chinese police. The security should be done by us, not them," said a senior Tory.

The alleged incident comes at a time when bilateral security cooperation has been planned between the two countries. Two People's Liberation Army officers have just graduated from the RAF officers' college at Cranwell in Lincolnshire. Chinese officers are also now likely to train at Sandhurst and Dartmouth, the army and naval training colleges in UK. Interestingly, during last week's official state visit, British Prime Minister David Cameron and Chinese President Xi had pledged the end of 'cyber-enabled theft of intellectual property, trade secrets or confidential business information'.