Mayor of London Sadiq Khan has asked Scotland Yard to be “extra vigilant” for any rise in cases.
The National Police Chiefs’ Council (NPCC) revealed there was an increase of reports to an online hate crime reporting site between Thursday and Sunday compared to the corresponding period four weeks ago.
Poland’s ambassador to Britain has expressed shock at “xenophobic abuse” against the Polish community, while David Cameron condemned incidents of abuse and hatred directed at migrants and Boris Johnson said he was “appalled” by reports of an increase in crimes of racism and xenophobia over the weekend.
Mr Khan called on Londoners to “pull together and rally behind this great city” and stressed it was “crucial” not to “demonise” the 1.5 million people in London who voted for Brexit.
“While I and millions of others disagreed with their decision, they took it for a variety of reasons and this shouldn’t be used to accuse them of being xenophobic or racist,” he said.
Cambridgeshire Police is investigating after cards reading “Leave the EU – no more Polish vermin” were discovered.
An 11-year-old boy named as Matteus, whose family moved to Britain from Poland three years ago, said he was going to school when he found a card containing the words on Friday.
The boy’s father Tomek said: “I live in this country, I pay any taxes. My home is now this country. I do not understand this situation.”
Scotland Yard is investigating a hate crime incident after offensive graffiti was daubed on the front of a Polish Social and Cultural Association in Ravenscourt Park, west London.
The force said the suspect involved was captured on CCTV at the scene. It shows him spraying yellow graffiti on the doors of the community centre before making off on his bike. Police foot patrols have been stepped up in the area.
Polish ambassador to Britain Witold Sobkow said: “We are shocked and deeply concerned by the recent incidents of xenophobic abuse directed against the Polish community and other UK residents of migrant heritage.”
Other incidents were reported on social media and a hashtag of #PostRefRacism was being used on Twitter.
One user, James Titcombe, posted: “Daughter tells me someone wrote ‘(Child’s name) go back to Romania’ on the wall in the girls’ toilets at school today.”
The NPCC said there were 85 reports made to True Vision, an online hate crime reporting site, between Thursday and Sunday – a rise of 57 per cent compared to the 54 made on the corresponding four days four weeks ago.
The organisation said the figures only take into account reports made through one mechanism and should not be read as a national increase in hate crime of 57 per cent.
Assistant Chief Constable Mark Hamilton, national lead for hate crime, said: “At the national level, the vast majority of people are continuing to go about their lives in safety and security and there have been no major spikes in tensions reported.
“However, we are seeing an increase in reports of hate crime incidents to True Vision.
“This is similar to the trends following other major national or international events. In previous instances, crime levels returned to normal relatively quickly but we are monitoring the situation closely.”