Hong Kong, Sep 1 (IANS): At least 40 people have been arrested for "participating in an illegal assembly, destroying property and obstruction of justice" inside the Prince Edward metro station in Hong Kong, police said on Sunday.

Video footage showed members of the police's Special Tactical Squad, known as "raptors", charging into a stationary train at Prince Edward station on Saturday night, reports the South China Morning Post.

One clip showed officers from the squad hitting two men and two women in masks who were crying and cowering on the ground, while one officer pepper sprayed them.

As the officers left the cabin, other passengers, some of them masked, could be seen with their umbrellas up.

Other footage showed several commuters bleeding from head wounds, and officers tying up suspects who had been wrestled to the ground.

Police said they entered the station as there were protesters destroying ticketing machines and the control room window, and said they had received emergency calls about a dispute in the station. The Mong Kok MTR station was also vandalised.

"We disagree with the allegations police officers had entered the MTR stations to beat people up," a police spokeswoman said.

"The officers used their professional experience to distinguish protesters who had changed clothes from ordinary commuters."

However, she later acknowledged it was difficult to differentiate protesters from ordinary citizens or reporters at the scene, and said officers had used force and pepper spray to arrest protesters after being attacked with umbrellas.

Soon after, many railway services ground to a halt as the MTR announced the suspension of three more lines - Island, South Island and Tseung Kwan O - following the earlier closure of the Tsuen Wan and Kwun Tong lines, the the South China Morning Post reported.

Saturday's incident was just one of many shocking turns during the 13th straight weekend of ­protests in the city against the now-shelved extradition bill.

Anti-government protesters are planning on Sunday afternoon to disrupt all travel routes to Hong Kong airport.

Protesters are calling on the public to overwhelm road and rail links to the airport on Sunday and Monday to cause flights to be cancelled.