The MTR said the supervisor suffered injuries to his hands and neck.

“This is the first time an MTR employee has been physically attacked by the protesters,” said Tam Kin-chiu, the union’s vice-chairman.

The latest incident happened hours after the city’s embattled leader, Carrie Lam Cheng Yuet-ngor, announced the formal withdrawal of the extradition bill that sparked months of protesting in the city.

Tam said the incident showed Lam’s concession had done little to ease the rising tensions between protesters and the government, and radical protesters now see the MTR Corp as an enemy in league with a police force they have battled in the streets for months.

“It seems that Lam’s concession hasn’t had any effect on softening the tensions, therefore we urge the government and the MTR Corp to get tougher on the protesters to safeguard staff safety, including deploying more police at every station, like they did for this week’s citywide strike,” Tam said.

In recent weeks, the rail giant has had its services disrupted, stations vandalised and its corporate image tarnished. Over the weekend, more than 40 railway stations – amounting to more than 40 per cent of the heavy rail stations in Hong Kong – were severely damaged.

The MTR Corp has obtained an injunction to prevent interference in its operations ahead of any potential violence, and made ad hoc arrangements to suspend services and close stations because of protests or rallies.

In turn, protesters have stepped up their attempts to cripple rail networks by damaging the station facilities including security cameras, ticket machines, glass doors, turnstiles and station control rooms.

Last weekend, some threw objects onto the tracks – causing the suspension of several rail lines and looted fire extinguishers and defaced stations.

The pro-Beijing union submitted a petition to Lam on Thursday, with its representatives, including Michael Luk Chung-hung, meeting with senior officials from the Transport and Housing Bureau.

Tam noted radical protesters also used various tricks to frustrate rail operations, such as using objects to clog the MTR toilets, jamming station hotlines, applying glue to Octopus sensors at turnstiles, and the intercom and emergency buttons, hanging objects over the overhead cables to stop the trains, and even pointing lasers at drivers.

“Pointing lasers at the drivers is very dangerous,” Tam said.

However, what the staff and the rail giant feared most was hard objects being thrown onto the tracks, he said.

“This is highly dangerous. The objects on the tracks may cause a moving train to derail and even overturn. This is the biggest concern of the company. I beg the protesters go to find the management to express their discontent and not to harass the station staff as we are just small potatoes,” Tam added.

To protect staff, the MTR Corp has enhanced the provision of protective gear, such as goggles and masks, and has also installed protective layers to strengthen glass doors and windows.

“If the protesters jump over the turnstiles without paying, we’ll just let them be,” he said. “If staff are surrounded by protesters, they will retreat to the staff control rooms and use the indoor escape routes to leave the station.”

However, a rail driver who wished to remain anonymous, accused the rail operator of siding with police, and said it was to blame for exposing frontline staff to danger.

“So far the MTR has only thanked the police, but it never mentioned the injured passengers,” he said. “It is also trying to evade responsibility by refusing to make public the CCTV footage of the Prince Edward station on August 31 and the Yuen Long station gang attack on July 21. It is the MTR who stirs up the public hostility against itself.”