Ukip MP Douglas Carswell surrounded by anti-austerity protesters in London

The Ukip MP, Douglas Carswell, has been escorted away in a police van after he was surrounded by anti-austerity protestors in central London.

Carswell later tweeted that he had been waiting for a bus when he was attacked by a crowd, describing it as “very very nasty”.

The MP said he had been engaged in peaceful discussions with a small group before being confronted by far larger numbers shouting insults such as “Ukip scum”.

“It got extremely, extremely nasty. Their intentions were pretty murderous and I needed a lot of police officers to prevent them from attacking me,” he said, after being taken by officers to another stop to get his bus.

“I was stunned. I think MPs should be able to go about their business. It was incredibly intimidating. It was like a lynch mob on the streets of London. I thought this was a country where we had democracy and discussed the issues.

“It just got incredibly ugly. It was an attempted lynching. I am in a state of shock. I do not want to have to worry about going about my business.”

The journalist Harry Cole was on the scene and filmed the incident, and later posted it on Twitter.

The incident was one of a number of flashpoints involving skirmishes between police and protesters among the several thousand who took part in a demonstration in the Trafalgar square area against government austerity measures set out in the Queen’s speech.

Police drew batons and linked arms to form a human barricade as protesters, some wearing masks and scarves to cover their faces, ran down Whitehall.

Police said they made three arrests. They included a 45-year-old man who had been wanted on suspicion of violent disorder in Whitehall on 9 May. The others were a 17-year-old, arrested on suspicion of assault on police, and a man who was arrested on suspicion of violent disorder and possession of an offensive weapon.

About 200 people took park in a second, smaller protest held outside Downing street, which was attended by union leaders and politicians, including Green party leader Natalie Bennett. © Guardian News and Media Limited 2010