BEIJING — Britain has asked China to open an inquiry into the death in November of a British citizen linked to the family of Bo Xilai, the Chinese Politburo member whose dismissal this month as Communist Party secretary of Chongqing was widely said to reveal a deep split among the nation’s leaders.

Britain’s request was lodged early this year but became public only on Monday, as accounts emerged that a principal player in the scandal that led to Mr. Bo’s dismissal had claimed that the dead man, Neil Heywood, had been poisoned.

After Mr. Heywood was found dead in his hotel room in Chongqing, a province-level region in south-central China, the authorities ruled that the cause was alcohol poisoning. In Internet posts and interviews, however, people who knew him said he had not been a heavy drinker. In an interview on Monday, an acquaintance described him as an associate of Mr. Bo’s family for more than a decade who had assisted in the overseas education of the younger of Mr. Bo’s sons.

On Monday, a spokesman for the British Foreign Office said the government had sought a new inquiry “based on concerns raised to us privately by British citizens in China.”