Panel members are expected to use the meeting to decide if some form of independent inquiry is needed to get to the bottom of what really happened in the Tsim Sha Tsui underpass in the early hours of March 17.

They are also keen to find out what was behind the shootings and the links to earlier crimes, including two other murders and a bank robbery, all involving the gun stolen from a slain police officer in 2001. They will study press coverage of the shootings and look at what options are available for some form of non-police investigation into the shootings in a bid to allay public concern that they are not getting the full story. Another option is a full Legco inquiry.

Police initially insisted Tsui was a 'rogue' cop who ambushed constables Tsang and Sin for their service revolvers. However, yesterday in answer to questions from the Sunday Morning Post their position shifted slightly to saying that 'our investigation to date shows that Tsui acted alone'.

The Post has learned from separate sources that the underpass gun battle came after a pre-arranged meeting which was called to discuss soccer betting. We also revealed last week that a major investigation into soccer betting in 2000/2001 was 'buried' after the scale of the problem in the force became clear to police top brass.

Three bank accounts in Tsui's name containing substantial amounts of money have been seized by police and the Post understands these are connected to a soccer betting operation.

The police have not denied the soccer betting link and only said that they have 'found no evidence so far to prove' a link.

The force has also seized a van and a motorcycle. They say Tsui used both before the shootings, but sources told the Post a man was seen driving away from the scene afterwards.

Police have refused to answer detailed questions on the case, saying they do not want to prejudice a likely death inquest, but they have already said Tsui was involved in earlier crimes.

Security panel chairman James To Kun-sun said he had taken legal advice and it was likely the panel would explore the possibility of using a previously unused provision in the Coroner's Ordinance, which allows the Coroner to step in early in an inquiry if 'he feels it is in the public interest'.

'Our legal advice is that this provision has not been used before because it is a new provision. I am now putting together the papers for the meeting, which will take place on Friday,' Mr To said.

Police said in a statement 'the force is ready to assist Legco in the discharge of its functions'.

The move to have the issue discussed by a special meeting has received the backing of another panel member, Civic Party leader Audrey Eu Yuet-mee, and key party member Ronny Tong Ka-wah.

'Whether the matter has reached the stage where we need a commission of inquiry, I am not sure,' Ms Eu said. 'We should have trust in the police. But there are areas of concern and I would say a meeting of the security panel is justified. A public inquiry would be difficult to justify to the public at the moment but a panel meeting to air things, yes.'