The actions of Tang King-shing yesterday make him the first police commissioner ever to say sorry in public.

The apology by Tang came after five civilian drivers were ordered to form a roadblock to stop illegal car racers in their tracks.

Their vehicles - three taxis, a lorry and a car - were stopped by police and used to block the three lanes of the Kwun Tong Bypass shortly before 2am on Monday. The drivers remained in the vehicles, which were struck by three cars believed to be involved in illegal racing.

The resulting pile-up and chases to two other roadblocks led to eight people, including a taxi driver and two police officers, being injured.

"According to initial investigations and the information we have gathered so far, we believe there has been some error in judgment in our operation," Tang said.

"I apologize to the citizens affected, including the drivers involved in the traffic accident and the car owners."

But in an attempt to play down the police role, he said road racers had endangered not only their own lives but also those of the public.

Officers had received numerous 999 calls about the road race and had to make a quick decision.

However, he promised to review the force's operational procedures. "In any police operation, our aim is to protect life and property. The safety of the public is one of the key elements we take into account," Tang said.

Though he did not promise compensation, he has instructed a district commander to assist drivers and car owners, subject to the all clear from the Department of Justice.

A source close to the police said an internal investigation will be conducted to determine whether anyone has breached internal procedures.

Meanwhile, there are questions as to whether the setting up of the roadblock satisfies the occupational safety requirements of frontline police officers. "A police officer should always be able to protect himself, before he can protect the lives of others," one veteran officer said.

Police public relations branch chief superintendent Ng Ka-sing also apologized yesterday to those caught up in the roadblock.

If an investigation determines the police are responsible for the pile-up, they will accept responsibility and help pursue any damage claims, Ng said.

Taxi and Public Light Bus Concern Group chairman Lai Ming-hung said some drivers have complained before about being used by police to block roads but that, in most cases, approaching vehicles made U-turns in time.

Hong Kong Police Inspectors Association chairman Tony Liu Kit-ming, who is also the chief inspector at Kowloon East traffic division, said the incident has damaged public opinion of officers. Liu said the police will learn from the experience and avoid such a thing from happening again.

The five men held on suspicion of furious driving were last night released on HK$10,000 bail and must report back to the police at the end of the month.