Hong Kong airport suspended check-in for all flights on Monday due to a massive protest that began in earlier in the day and disrupted operations in its arrivals terminal.

Police also fired tear gas into subway stations, posed as protesters, and arrested at least 12 protesters in the last day. The flight cancelations left many visitors stranded in the airport, surrounded by scores of protesters.

But while Hong Kong law states that the PLA troops stationed here can not interfere in local affairs, it does allow for their deployment at the request of the Hong Kong government to "maintain public order".

The Hong Kong Airport Authority has announced that all flights out of Hong Kong will be cancelled for the rest of Monday owing to a large number of protesters at the airport. There are unconfirmed reports she could lose her right eye as a result of the injury.

However, the Hong Kong government has refused protesters' demands for an independent inquiry into the police actions.

It is the eleventh week of the pro-democracy movement.

Shares of Hong Kong's dominant airline traded down 4.9% Monday, closing at their lowest price since June 2009.

There have already been rumours that such an exercise is underway, leading the Hong Kong Police to issue a statement last week flatly rejecting "allegations" of mainland reinforcements among their ranks.

"China solemnly demands that the British side immediately stop all actions that meddle in Hong Kong affairs and interfere in China's internal affairs", said a Chinese foreign ministry spokeswoman.

By appealing to the worldwide community, and making sure it is their message that most foreigners are seeing, protesters have shown themselves adept at public relations.

Protesters hold a US flag as they gather in Tsim Sha Tsui in Hong Kong, August 3 in opposition to a planned extradition law that has evolved into a wider movement for reforms.

Mainland authorities have harshly condemned the demonstrators and Hong Kong's flagship carrier Cathay Pacific has found itself caught in the crossfire.

Protesters have called for her resignation in light of her introduction of the extradition bill.

They were responding to allegations that police were using increasingly violent tactics to suppress protests. Others hurled taunts and rocks, and shone laser pointers at officers' faces until squads of riot police pushed forward, dousing the crowd with tear gas.

Hong Kong was returned to China in 1997, but has since benefited from the "one country, two systems" approach that has spared the special administrative region from having to conform with many aspects of the mainland's authoritarian system.

The Hong Kong University Students' Union, made up of several local students unions from universities such as Hong Kong University and the Chinese University of Hong Kong, issued a statement on the morning on August 12, condemning the actions of the local police as "out of control" and "dehumanizing". The Communist Party's official People's Daily newspaper said on the Twitter-like Weibo that the force can handle incidents including riots or terrorist attacks. "What they gain is for [all of] us". Meanwhile despite carrying out regular press briefings, the Hong Kong government has at times appeared at a loss as to how to engage with residents and protesters.

Reporters and medics were also allegedly targeted and harassed by Hong Kong police.

"The police have told a lot of lies to Hong Kong people".