China's ambassador to the United Kingdom Liu Xiaoming said the radical movement in Hong Kong has become "neo-extremism" under the cover of a so-called pro-democracy movement and challenges the principled bottom line of "One Country, Two Systems".

Liu reaffirmed that the central government of China firmly supports the Hong Kong Special Administrative Region in quelling unrest in the city. He made the remarks at a news conference at China's embassy in London on Thursday.

"The neo-extremism is both highly deceptive and destructive," Liu said, referring to the violent protesters in Hong Kong that stormed the Legislative Council Complex, attacked the Liaison Office of the Central People's Government, assaulted police officers and brought Hong Kong airport to a standstill.

"Their moves are severe and violent offences, and already show signs of terrorism," he said.

Following his remarks, a short video was played showing a citizen and a journalist from the mainland and the Hong Kong police being attacked by protesters.

"The violent offenders must be brought to justice in accordance with law," Liu said, adding that radical behavior which undermines rule of law and social order is unacceptable.

Liu also said the SAR and central governments are fully prepared for the worst while hoping the unrest will end in an orderly way.

"Should the situation in Hong Kong deteriorate further into unrest (that is) uncontrollable for the government of the Hong Kong Special Administrative Region, the central government would not sit on its hands and watch," said Liu. "We have enough solutions and enough power within the limit of the basic law to quell any unrest swiftly.

"The priority now is to support the SAR government in ending violence and restoring order," Liu said, and reiterated the central government's trust in the SAR and Hong Kong police to handle the situation.

He said there was evidence that showed the situation in Hong Kong would not have deteriorated so much had it not been for the interference and incitement of foreign forces. "Foreign forces must stop interfering in Hong Kong's affairs," he stated.

"I want to reiterate here that Hong Kong is part of China; no foreign country should interfere in Hong Kong affairs," he said.

He urged media to report responsibly and be objective. "There has been massive coverage on the so-called' right to peaceful protest' but few reports on violent offences by extreme radicals, such as disruption of social order, attacks on police officers and injuries to bystanders," he said while pointing to video showed during the news conference.