LONDON (Reuters) - The number of hate crimes reported to British police in the run up to and aftermath of the vote to leave the European Union has surged by 42 percent, police chiefs said on Friday.

There were 3,076 incidents reported to forces nationally in the two weeks from June 16, an increase of 915 offences compared to the same period last year.

Britons voted on June 23 to leave the EU following bitter and deeply divisive campaigning in which immigration was a key issue with Muslims and Eastern European saying they had been particularly targeted.

“We now have a clear indication of the increases in the reporting of hate crime nationally and can see that there has been a sharp rise in recent weeks,” said Mark Hamilton, the National Police Chiefs’ Council spokesman on hate crimes.

“This is unacceptable and it undermines the diversity and tolerance we should instead be celebrating.”

The official number of reported crimes echoes the 500 percent rise in the number of incidents relayed through the police online portal in the wake of the Brexit vote.

Critics have accused some in the “Leave” campaign of stoking xenophobia and racism, as part of a message that leaving the EU would allow Britain to stop uncontrolled immigration, which many Britons blame for putting pressure on jobs and public services.

A week before the vote, opposition Labour lawmaker Jo Cox, a strong supporter of remaining in the EU, was shot and stabbed to death in her constituency in northern England.

Police said the peak number of hate crimes occurred on June 25 when 289 incidents were reported across the United Kingdom, but there had been a marked decline since then.

The most common offences were harassment, assault and other violence such as verbal abuse, spitting or barging.

Prime Minister David Cameron has promised to clamp down on hate crime and the issue has also been raised at a meeting of EU leaders in Brussels.