Police painted a grim picture of the last two weeks of June, saying reports of hate crimes rose by 42%, compared with the same period in 2015, in the lead-up and aftermath of the June 23 vote on whether to stay in or leave the European Union.
Authorities announced that 3,076 hate crimes were reported between June 16 and 30, or 915 more cases compared with the period in 2015, the National Police Chiefs' Council said.
Incidents of hate crimes had increased so much that police around the country were asked to submit weekly reports about their areas, the council said in a statement.
The council's head of hate crime, Mark Hamilton, said that police forces had heightened their response over the last 10 days.
"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. This is unacceptable, and it undermines the diversity and tolerance we should instead be celebrating," Hamilton said in the statement.
"Everyone has the right to feel safe and confident about who they are and should not be made to feel vulnerable or at risk."
Reports of hate crimes peaked two days after Britain voted to leave the European Union in a referendum, with 289 offenses across the UK that day alone, the council said. There has been a significant decrease since then, it said.
Much of the debate on "Brexit" had focused on the issue of immigration, with critics often accusing the "Leave" campaign of xenophobia and prejudice.
Scare at London mosques
The main type of offense recorded in the last half of June was harassment, common assault and other violence, such as verbal abuse, spitting and shoving, the council statement said.
The council's announcement on hate crimes came a day after as several mosques in London reported being sent white powder in envelopes, one with a racist term for Pakistanis and the word "filth" written on it and a picture of a mosque crossed out, British media reported
, adding that the powder turned out to be harmless.
Parts of the UK Parliament also were forced to close after a Muslim member of the House of Lords received a similar package that turned out to be harmless, reports said
"I simply will not tolerate hate crimes of any form, anywhere in London," Khan said. "We must stand together, and anyone who sees or is targeted by abusive behavior should report it to the police immediately."
There has been a backlash to the hate crimes, with social media hashtags and campaigns showing solidarity with minorities.
The hashtag #PostRefRacism was set up for people to share experiences of hate crimes after the referendum on the EU.
Others wore safety pins in a campaign to support safety in public for Britain's immigrants and ethnic minorities.