Chinese authorities in Chongqing have pledged to better protect foreigners after Briton Neil Heywood's death in suspicious circumstances sparked a dramatic political scandal.

Heywood's death in November has been linked to the wife of Bo Xilai, a top leader who has now been ousted from his elite position in the ruling Communist Party amid sensational allegations of corruption and abuse of power.

His wife Gu Kailai has been placed under investigation for the murder of Heywood, a British businessman who was on good terms with Gu and her son Bo Guagua but who came into conflict with them over "economic interests."

The Chongqing public security bureau has vowed to better protect foreigners who live or come to the megacity "for business, study or tourism," the official Xinhua news agency quoted an unnamed official in the bureau as saying.

The official said that apart from the Heywood case, "there have not been any violent crimes against foreigners in Chongqing since the start of 2010," the report said.

Heywood was found dead in a Chinese hotel room in what was initially blamed on excessive alcohol consumption. But the case took a shocking turn last week when Xinhua announced Gu was being investigated for alleged murder.

China is generally safe and foreigners rarely report any cases of violence against them.

But the mysterious death of Heywood has been classed as "a serious criminal case involving the kin and aides of a party and state leader", prompting a pledge to "thoroughly" investigate the scandal.

Bo, the son of a revered communist revolutionary, had launched a draconian crackdown on criminal elements in Chongqing and a "red revival" campaign marked by the mass singing of old Maoist-era songs.

Many analysts saw the moves as a bid for entry to China's inner circle.

The ruling party will complete a once-a-decade power transition later this year centering on a new line-up for the powerful nine-member Politburo Standing Committee that governs China and which Bo was widely tipped for.

But the rapid unravelling of his fortunes has exposed a harsh factional pushback against the charismatic and ambitious Bo, and the affair has been seen as a huge embarrassment for the party.