Fights break out at pro-Trump rally after organiser 'doused with pepper spray'

Fights broke out at a rally held by supporters of US president Donald Trump after an anti-Trump protester reportedly sprayed a female rally organiser with pepper spray at a popular California beach.

The fights began at the rally on a strip of coastline near Huntington beach after demonstrators encountered a small group of anti-Trump protesters.

Four of the counter-protesters were arrested, Kevin Pearsall, a spokesman for the California State Parks Police, said.

Park police estimated that 2,000 Trump supporters were present while around 20 counter-protesters attended.

Reports on the Los Angeles Times' website described a chaotic scene, while video posted on Twitter showed men fighting in the sand.

A group of Trump supporters appeared to chase a man in a black mask away from the beach. He was stopped by members of the California Highway Patrol, according to the LA Times said.

The newspaper reported the man had used pepper spray on a female rally organizer and was then set upon by a group of Trump supporters.