Hong Kong's former director of public prosecutions Grenville Cross praised the city's police force, saying the officers have shown "incredible restraint and great courage under huge provocation".

During a one-on-one interview with China Daily on Tuesday, the honorary professor of law at the University of Hong Kong also noted that criticizing the police for "whatever they do" is actually an attempt to undermine the law enforcers' morale and weaken their resolve to uphold the law.

Cross' remarks came at a time when the city's police force is facing a storm of criticism for allegedly using excessive force in dispersing the mobs in violent protests against the now-shelved extradition bill. The spate of protests, which broke out since mid-June, usually began peacefully but deteriorated into violent clashes with police when radicals vandalized public buildings, besieged police stations, blocked roads and hurled insults at officers.

"The police have exercised maximum restraint. They only moved to regularize the situations when they've actually been attacked, and when all demands for the protesters to back off have been ignored," said Cross.

He cited the police handling of a 15-hour siege of police headquarters in Wan Chai on June 22 as an example of their exemplary discipline. Starting from the afternoon, tens of thousands of masked protesters wearing helmets surrounded the building, threw eggs, sprayed graffiti bearing insults on the walls, and pointed laser beams at police officers standing on guard inside.

"If they (the police) had struck back, there could have been a bloodbath. But they remained inside for 15 hours and, in effect, did nothing," Cross said, noting if the United Kingdom Parliament or the United States Congress were similarly attacked, the police would have struck very hard indeed on anyone involved.

"So by comparison with the other police forces around the world, they (Hong Kong police) have shown incredible restraint and huge courage. I'm very proud of them," Cross added.

The police have also come under criticism for doing too little in handling other situations. Critics questioned where the police were when radical protesters stormed the Legislative Council building on July 1 and fled after leaving behind a trail of damage that would take several months to repair and cost an estimated HK$40 million (US$51 million).

Commissioner of Police Stephen Lo Wai-chung explained that "a temporary retreat" under the circumstances was necessary to avoid bloodshed in a melee.

There has been a concerted campaign mounted by the extremists and their apologists in the political parties to undermine the police morale, Cross said.

"So whatever they (the police) do, make complaints about them and denounce them to the local and international media. That is actually an attempt to undermine the law enforcers' morale and weaken their resolve to uphold law and order," Cross noted.

He advised the police to recognize the ploy of their critics and continue to do what is right and avoid falling into the trap of having their actions dictated by people who don't wish them well.

As of Tuesday, some 146 police officers had been injured in the line of duty. An officer had part of his finger bitten off by a radical protester resisting arrest on July 14 at Sha Tin, and has not been discharged from hospital.