Clashes follow Trump rally in California

 Supporters and opponents of Republican presidential nominee Donald Trump have clashed in San Diego, California with riot police being deployed to keep the rival camps apart.

Skirmishes flared following a Trump rally, with supporters and opponents confronting each other in the streets, trading insults with each other.

Police declared a gathering outside the city's convention centre unlawful, as stones and water bottles were thrown. 35 arrests were made.

The San Diego Police Department said that 35 arrests had been made and there was no damage to property and no injuries reported.

Trump has pledged to build a wall along the US border with Mexico to keep out illegal immigrants. San Diego's population is about one-third Latino and hundreds of thousands of people cross the border with Mexico legally each day.

Earlier on Friday, Trump backed out of an offer to debate with Democratic candidate Bernie Sanders.

"As much as I want to debate Bernie Sanders - and it would be an easy payday - I will wait to debate the first place finisher in the Democratic Party, probably Crooked Hillary Clinton, or whoever it may be," said Trump's campaign office in a statement.

Mr Sanders told reporters on the campaign trail that he hoped Mr Trump would change his mind.

"Well Mr Trump, what are you afraid of?" he said, calling the Republican nominee a bully.

The latest opinion polls suggest Clinton leads Trump by around four percentage points.