Hong Kong forensic experts have examined the bus where 8 tourists were killed just over a week ago. Their visit to Manila comes as recorded phone calls between the gunman and Philippine police negotiators is released. The recordings show how the former policeman became gradually enraged and started killing hostages.

A team of Hong Kong investigators have been given the green light to carry out their own investigation into the hostage ordeal.

On Monday morning, they met with their Philippine counterparts and then examined the bus for themselves. A crime scene on wheels.

The Hong Kong police have also asked for copies of all reports, to examine the firearms used in the 12-hour stand-off and interview witnesses.

Philippine Justice Secretary Leila de Lima has agreed to the request but says all work must be carried out in the company of Philippine police.

Authorities say autopsy reports should be made available this week.

Meanwhile, Hong Kong's Phoenix TV has released phone calls between the gunman, former senior policeman Ronaldo Mendoza, and police negotiators.

Mendoza first became enraged during a call with a negotiator who agreed to recheck Mendoza's corruption case instead of giving him his job back.

Mendoza was far from satisfied with the reply and warned of creating tragedy on the bus.

The first gunshot happened when the hijacker lost trust with negotiators. He discovered they didn't return a gun to his brother Gregorio, who is also a policeman. Mendoza called the shot a warning.

He finally lost his cool when his brother was detained by police. Mendoza said his brother had nothing to do with the incident and warned of killing hostages as retribution.

He was told continuously to calm down on the phone, but didn't. Mendoza had only killed two hostages at that point and knew the bus was surrounded by police. He said he didn't understand why his brother was detained, and then hung up.

Some Hong Kong senior police officers have said the Philippine police's handling of the incident was full of mistakes. They also question why they didn't attack the hijacker as soon as he fired the first shot.