Police attributed increase in part to greater vigilance by officers and awareness among the public.
Hate crimes surged in Britain before and after the June 23 EU referendum, police said on Friday, following a campaign dominated by a divisive debate about immigration.
Although police attributed the increase in part to greater vigilance by officers and greater awareness among the public, more than 3,000 incidents were reported to police across the country between June 16 and 30, up 42 per cent on the same period last year, according to the National Police Chiefs' Council.
"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 council's lead officer on hate crime.
"This is unacceptable and it undermines the diversity and tolerance we should instead be celebrating."
Anti-racism campaigners had previously reported a surge in attacks, from verbal abuse to physical attacks, in the days after Britain's vote to leave the EU.
Prime Minister David Cameron had raised the issue in parliament, citing "despicable" graffiti daubed on a Polish community centre and abuse directed at members of ethnic minorities.
"We will not stand for hate crime or these kinds of attacks, they must be stamped out," he told lawmakers.
There was a peak in reported offences on June 25, the day after the referendum result was announced, when there were 289 incidents. The numbers have since declined.
The most common of the 3,076 offences reported was harassment, including assault, verbal abuse and spitting.
On Thursday, envelopes including messages of abuse and white powder were sent to several London mosques and a Muslim member of the House of Lords, sparking security alerts across the capital.
Police said Friday that substances found in packages delivered to a number of government, religious and other buildings had been found to be "not noxious or suspicious" and there were no injuries.
"There are a lot of very frightened communities in Britain," opposition Labour leader Jeremy Corbyn said in a speech to a pan-European socialist conference in Paris.
'Acceptable Behaviour'Nils Muiznieks, human rights commissioner for the Council of Europe -- a European forum on democracy and rights -- on Friday condemned the "racist rhetoric" that emerged during the Brexit campaign.
"Leave" campaigners, including senior Conservatives and the anti-immigration UK Independence Party (UKIP), had highlighted the benefits of being able to end the mass influx of European workers into Britain.
The Syrian refugee crisis also featured in the debate. The Brexit camp issued leaflets and an online video warning that tens of millions of Turks would be on their way if Turkey joined the EU.
"The debate running on Brexit was very scary because you had racist rhetoric about migrants and migration from the highest political level in UK," Muiznieks told reporters in Athens.
He added: "It's a signal (about) what is acceptable and what is not acceptable behaviour, and we saw in the UK the cost of this discourse."
Parts of the Houses of Parliament were locked down on Thursday after a Muslim peer, Nazir Ahmed, received a letter containing racist abuse and white powder.
It proved harmless but Ahmed told AFP it had been "frightening".
The Noor Ul Islam mosque in Leyton, east London, said it had received a similar package the same day.
The Evening Standard newspaper reported similar letters sent to a mosque and a Muslim organisation in north London.
Muiznieks said the Council of Europe had written a "long memorandum" to the British government on the "stigmatising" language it used about migrants.
Cameron was widely criticised last year after referring to a "swarm" of people waiting in the French port of Calais to cross the Channel to Britain.
"My concern is that it sends a signal to populist parties around Europe," Muiznieks said.