Some of the victims of the hijacking of a Hong Kong tourist bus in Manila, which turned into a hostage crisis, may have been hit by police fire, the Philippine investigators admitted for the first time on Thursday.

A Philippine policeman who had been dismissed from his job took a busload of 21 Hong Kong tourists hostage on Aug 23, killing eight of them and injuring several others by the end of the standoff. The gunman was killed in the final police assault.

"There is a distinct possibility that there was friendly fire," said Philippine Justice Secretary Leila de Lima, who added that the bullet trajectories and the hostages' wounds indicated that some of the victims could not have been hit by the hostage-taker, AFP reported.

As head of an official inquiry, she said the forensic reports on some of the victims did not match the account of the bus driver, who told investigators the gunman shot the tourists at close range.

De Lima noted that blood would have splattered all over the seats and windows of the bus if the hostages had been shot at close range, while dry blood was found only on the seats and floor of the bus.

When asked whether some of the victims might have been killed by the police, de Lima said: "We are not focusing (on that), but we should never miss that. Otherwise our report will be less than thorough."

The investigation team will await a complete ballistics report before drawing any final conclusions, she added.

The latest details of the investigation came as Philippine President Benigno Aquino III said on Thursday his government had initiated efforts to improve the police's ability to handle similar hostage incidents in the future.

"Our government is now focusing on taking the necessary steps to prevent this kind of tragedy from happening again," Reuters quoted Aquino as having said.

Sun Yi, spokesman for the Chinese Embassy in the Philippines, told China Daily on Thursday that China expects the Philippines to deliver a comprehensive and accurate report on the hostage incident as soon as possible.

However, the embassy does not set a timetable for the Philippines, Sun added.

Liu Jianchao, Chinese Ambassador to the Philippines, who met with Aquino on Wednesday afternoon, said: "We hope that the Philippine side presses ahead with the investigation and produces a comprehensive and fair report, which tells the truth and upholds justice."

Aquino stressed that the Philippines will work closely with China on the investigation, ruling out the possibility of a cover-up.