The interim injunction, effective until 30 August, also forbids people from “damaging any property or trains and using any threatening, abusive, obscene or offensive language or wilfully interfering with the comfort or convenience of any MTR staff at any station”.

The MTR made the move as Chinese state media issued a warning to the rail operator against any attempt to facilitate what they called “rioters” in destabilising actions, otherwise the company would run the risk of “derailing and slipping into the abyss”.

There was chaos again at Kwai Fong station, after the MTR decided to suspend services early at 9pm to head off a repeat of the previous night’s protest.

But even after the station was closed, protesters already inside stayed behind to besiege the control room, vandalising the premises and demanding to be allowed to use trains.

Protesters demanded staff inside the control room come out and explain the reason for closing the station.

When there was no response from staff, protesters started banging the control room window using umbrellas.

They also accused the staff of not allowing them to use the toilet, with many shouting that they needed to urinate and change sanitary towels.

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Some protesters started sticking sanitary pads to the window and also pointed laser pens at it.

Firefighters and ambulances arrived at the scene at around 10pm and left soon after. The staff inside the control room then announced through the PA system that they had called the police and urged people to leave the station as soon as possible.

At around 10.39pm, protesters inside the concourse rushed out after police in riot gear showed up outside the station. The MTR staff also told protesters they were taking part in an unlawful assembly

That was after the MTR issued a statement strongly condemned protesters who stormed Kwai Fong station on Thursday night, vandalising facilities such as the entrance gate and hurling expletives at rail staff. The rail operator said their actions had undermined the safety of MTR staff and passengers.

About 200 protesters swarmed the station to demand the MTR Corp explain why police were able to fire tear gas inside the station on August 11, resulting in the temporary closure of two exits.

“In light of recent repeated instances where station facilities were vandalised, MTR staff harassed and the safety of staff and passengers threatened … the MTR Corp is taking all necessary action, including taking appropriate legal action and making suitable regulation of station and train service operations if the situation so warrants,” it said.

“We support proper enforcement of the law against these illegal activities and reserve the right to take suitable legal action and seek suitable legal redress from the courts, including, if appropriate, injunctions to ensure that the safe and proper operations and use of our network can be assured.” Transport minister Frank Chan Fan also weighed in, saying various MTR stations had been attacked and suffered damage, with staff abused by protesters.

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“Due to these effects and safety threats caused to residents, their staff and passengers, the MTR Corp is handling the injunction work,” he said, adding that the measure was mainly to ban or prevent illegal actions from interfering with passengers’ journeys.

The rail firm took a tougher stance against protesters, with operations director Adi Lau Tin-shing holding an urgent meeting with unions on Friday after announcing that services could be stopped and the station immediately closed without prior notice in the event of “fights, vandalism or other acts of violence”.

The MTR followed the example of the Airport Authority, which secured an injunction to stop anyone from obstructing or interfering with operations at Hong Kong International Airport. On Friday, the injunction was indefinitely extended by the High Court.

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The MTR Corp, in which the Hong Kong government has a 75 per cent stake, has come under increasing pressure to get tough on protesters as Beijing expressed dismay at its softly-softly approach to dealing with their actions at stations.

The mainland Chinese media has launched scathing attacks on the rail firm, criticising it for being lenient with protesters and even providing an escape route for those who attack police, causing havoc in its stations and then taking free train rides to safety.

In a news broadcast late on Thursday night, CCTV anchor Ouyang Xiadan issued an unusual warning directly at the rail operator.

“The MTR dared to arrange special train services for the rioters and even sent them home free of charge. Some netizens said: ‘MTR, you have run off the rails!’,” she said.

“What is the next step [for the MTR]? It should think twice because if it messes up, the chances of derailing and slipping into the abyss are not impossible.”

However, some MTR staff have also been unhappy with the company’s response to police actions in station premises.

Following a joint petition by 700 drivers last week urging the rail company to condemn the use of force by police, such as deploying tear gas against protesters inside stations, more than 200 station officers submitted a second petition over the same demands to management on Friday.