A British National Party (BNP) member was attacked with a hammer when protesters arrived at a campaign event in Greater Manchester.
Violence broke out as 30 people surrounded a BNP vehicle outside the Ellesmere Pub in St Helens Road in Leigh on
Friday evening.
Tony Ward, 48, was hit with a hammer and later treated in hospital.
A 25-year-old man was arrested on suspicion of causing grievous bodily harm, Greater Manchester Police said.
Officers arrived at the pub to discover the BNP's trailer had been overturned, said a police spokesman.
A traffic diversion was put in place on St Helen's Road, while the trailer was removed and the road was closed. It has since reopened.
One witness told BBC News: "They had hammers and they smacked the vehicle to pieces, smashed all the windows and tore off the bumper, completely decimated it.
"I was shocked at what I saw."
A BNP fundraising event had been due to take place at Pure nightclub in Leigh, but it was cancelled at the last minute.
Simon Darby, the party's deputy leader said: "This was a violent attack by a group of thugs in which one of our members was badly injured.
"But we will not be put off."
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