The Police Force is determined to handle any untoward incidents and to maintain law and order, Secretary for Security Ambrose Lee said, adding it is regrettable some demonstrators had used excessive violence in a public procession on the first day of the WTO's Sixth Ministerial Conference.

Talking to the media this evening at Central Government Offices, Mr Lee said the Police had exercised tolerance and restraint in handling the demonstration.

He called on demonstrators to respect the laws of Hong Kong in their activities in the next few days, and to adopt a peaceful and lawful approach to express their views.

Chief Superintendent of Police Alfred Ma said he regretted some protesters had expressed their views in a non-peaceful way, adding their irresponsible behaviour would not win Hong Kong people's sympathy.

He said about 100 protesters tried to push a wooden object estimated to weigh several hundred pounds through the line cordoned off by Police.

When protesters set the wooden object ablaze, Police took immediate action, he said, adding the protesters' action was unacceptable and constituted a threat to the public safety.

To prevent the incident from deteriorating, Police resorted to using a minimal degree of force by spraying foam to stop protesters from pushing forward. The foam causes skin irritation, Mr Ma said.

Two police officers suffered minor injuries in the incident. Three other people were injured, and three were hospitalised.

No arrests were made so far, he said.

Mr Ma said Police will continue to assess manpower-deployment needs for the upcoming demonstrations.

He stressed Police use of force is governed by strict guidelines and officers are careful when they must apply it.

Police will continue their dialogue with the protesters' representatives and remind them to express their views peacefully.