Hong Kong-born Bob Chan said it left him bruised and fearing for his family’s safety. Some of the thugs were trying to take down banners.
At a press conference with Conservative MP Iain Duncan Smith, Mr Chan said: “I found myself being dragged into the grounds of the consulate.
“I held onto the gates where I was kicked and punched, I could not hold on for long. I was eventually pulled onto the ground of the consulate.
“I felt punches and kicks from several men.
“Other protestors were trying to get me out of this situation, but to no avail.”
He said the attack on Monday only stopped when a police officer got involved.
The demonstrators – many from Hong Kong – were protesting as the ruling Communist Party congress began in Beijing. UK police are investigating the incident.