The officer arrived to deal with a nuisance complaint about the man, who had been sleeping rough on a hillside in Ho Man Tin, shortly after 12.30pm yesterday.

Police chiefs say when the constable - who has been in the force for 11 years and works at Kowloon City station - tried to check the man's identity, he lashed out with his fists and then with the chair.

"The officer tried to subdue the suspect with pepper spray, but failed," Kowloon City Deputy District Commander Wong Chun-chin said. "The officer then used his baton and pepper spray again, but the suspect continued to attack him. The officer drew his revolver after warning and fired two shots, one of which hit the man's head."

Police confirmed that no knives or guns were found at the scene in Ma Tau Wai Service Reservoir Playground at 2 Sheung Wo Street, near Mau Tau Wai Pumping Station, just opposite Lok Man Sun Chuen in Ho Man Tin. Wong confirmed that no attempt was made to snatch the officer's gun.

The vagrant, thought to be of South Asian ethnic origin and in his 30s or 40s, has not been identified because he was carrying no documentation. He died in Queen Elizabeth Hospital at 6.43pm - six hours after he was shot.

The officer sustained hand and back injuries.

Asked if he thought the officer had exercised professional judgment before opening fire, Wong said an officer is justified in using his revolver when other means to subdue the suspect fail and he feels his life, or that of anyone else, is being threatened. "Of course he wouldn't deliberately shoot [the suspect] in the head, but in the spur of moment it's difficult to say where the bullet will hit," Wong said.

The officer had pressed his emergency button for backup.

Kowloon City district councillor Yang Wing-kit said he had received five complaints since January about a homeless man causing a nuisance by yelling and changing his clothes in public. "Yet we never heard anything about the man being violent or displaying obscene behavior," Yang said.

Tony Liu Kit-ming, chairman of the Police Inspectors' Association, said a bottle of OC Foam, or pepper spray, which can be used about 10 times, may be unable to subdue a suspect. "If the suspect is drunk, has psychiatric problems and is extremely agitated, the spray may not have any effect," Liu said.

James To Kun-sun, Legislative Council security panel vice chairman, said the police officer could have avoided drawing his revolver.

"If the suspect is not a fugitive there is no need to rush to subdue him when it's a one-on-one situation. He doesn't have to subdue the suspect on his own,"To said. "He could consider moving away from the attack and waiting for support."

Death prophecy

A note found at the scene appears to be a mix of Nepalese and a dialect - possibly Gurung - one interpretation being: "If somebody dies, the family must stay home and fast."