Chinese police are investigating whether a fiery car crash which killed five people and injured dozens was linked with suspects from the country’s restive Xinjiang region, with mounting evidence pointing to a deliberate suicide attack.

Police issued a notice late on Monday ordering Beijing hotels to check their records for a 42-year-old and 25-year-old from Pishan and Shanshan counties in the far western province, in connection with an unspecified "major incident".

While official channels have restricted details of the case, and sensitive online posts about the incident are still being swiftly removed by censors, a state security source with knowledge of the investigation told Fairfax Media that at least two of the dead car occupants were Uighurs – a predominantly Muslim ethnic minority – from Xinjiang.

The source said there were suspicions the incident was connected with terrorist activity, but that it was not yet confirmed.