Around 50 Occupy London protesters were evicted last night and went peacefully from the UBS-owned building which the group had turned into what it called a ‘Bank of Ideas’.

Despite apparently meeting no resistance, police and bailiffs were said by demonstrators to have used “heavy handed” tactics.

Occupy London protesters claim a photographer Jules Mattsson was punched in the face by a bailiff who then drove his car at speed towards more protesters.

Mattson reported the incident on Twitter (twitter.com/julesmattsson) and posted a link to this video which apparently shows the bailiff driving his car at a group of people. Mattson claims he also has footage of the alleged assault.

It is thought that the bailiff has been arrested.

A spokesman for the Metropolitan police said a man was detained after an allegation of assault and criminal damage. Another man, believed to be a protester, was briefly arrested “to prevent a breach of the peace” but was released soon after.

On Twitter, Mattson wrote: “I am, obviously, pretty pissed off about this all. I have a right to go about my job covering news without fear of assault.”

This morning, the Occupy movement issued this statement: “We are also gravely concerned that the police’s actions this morning demonstrated a greater concern for the well-being of a building than the safety of the public. We look forward to receiving a formal response.”

Occupy London took over the abandoned office block in November in protest against the government and banking industry’s response to the financial crisis.

The UBS building was seen as appropriate as an appropriate target as the bank was implicated in the sale of shared appreciation mortgages during the 1990s, a practice that left many pensioners too poor to move to more suitable accommodation, according to critics.