HONG KONG, Friday 3 September 2010 (AFP) - Hong Kong police will study bullets test fired from guns used in the Manila hostage bloodbath, reports said Friday, amid anger over the crisis that left eight of the city's tourists dead.

The incident, which sparked a diplomatic meltdown between Hong Kong and Manila, has raised questions about whether the tourists were killed by a lone gunman -- disgruntled ex-cop Rolando Mendoza -- or by police during their botched rescue operation on August 23.

Mendoza was shot dead by Philippine police, ending a 12-hour standoff drama played out on live television around the world.

Two police officers from Hong Kong on Thursday brought back spent shells after test firing Mendoza's weapons, an M16 assault rifle and .45 calibre pistol, the city's media reported.

The officers were held up at the airport in Manila on Thursday on doubts over whether they had clearance to take the bullets and casings out of the country.

"Mr Li Kwai-wah, chief inspector from Hong Kong, was actually authorised to bring those shells with him to Hong Kong. They have a clearance from the Philippine National Police," Philippine Justice Undersecretary Jose Vicente Salazar said Thursday.

"It was just that, at this time, all those items related to the (bus hijack) investigation being brought out must be cleared by the Department of Justice."

Salazar added that the police officers were later granted clearance to take the bullets to Hong Kong.

"In fact the (Chinese) police attache admitted that they failed to obtain (justice department) clearance," he said.

Philippine authorities admitted to a string of blunders in handling the crisis, which has strained relations with Hong Kong and pounded the southeast Asian nation's tourism industry.

Philippine authorities said they expected to wrap up their inquiry on Monday.