London CNN  — 

Police in Britain have recorded a dramatic rise in racist attacks in the wake of Brexit, with five times the usual number of incidents reported in the week since the country voted in a referendum to leave the European Union.

The National Police Chiefs’ Council says 331 cases have been reported to the True Vision anti-hate crime website since last Thursday, compared to the regular weekly average of 63.

It is not clear how many of those 331 attacks are linked to the referendum, but there have been several high-profile cases tied to the vote for Brexit, the combination of words for Britain and exit that refers to the United Kingdom leaving the European Union.

More than 17 million British voters (52%) backed Brexit in last week’s referendum on breaking away from the EU.

A Polish community center in London was daubed with offensive graffiti, and Polish immigrants in several towns and cities were targeted.

“We have had reports and we’ve seen pictures of notes being pushed through people’s doors, describing them as vermin, as scum, and of verbal abuse,” Joanna Mludzinska, who runs the London center, told CNN.

Chief Constable Sara Thornton, head of the NPCC, said “loud and passionate” debate was to be expected, given that the country was in “a period of unprecedented change,” but that there was no excuse for racism or hate crime.

“Like the vast, vast majority of people, I have been shocked and disgusted at some the cases of racial or anti-immigrant abuse that have been reported this week,” she wrote in a blog on the NPCC’s website.

“I’ve heard of a small number of people this week saying they feel scared to leave the house … our message to them is don’t give way to bullies and don’t suffer in silence. We will protect you.”

A Twitter group, Post Ref Racism, and accompanying hashtag, #PostRefRacism was set up to share reports of abuse after the Brexit vote.

Economist Marianna Koli has lived in the UK since moving from her native Finland when she was 18. Days after the Brexit vote, she experienced what she says was her first racist incident in 16 years.

“I was walking in my local high street, talking to a friend of mine – we were speaking English – and a chap just behind me shouted ‘I like your accent’ in a very loud voice – I did feel it was a bit threatening.

“It very clearly wasn’t intended as a compliment. He was saying ‘I see you, I’ve noticed you, that you are foreign, and I would like to tell you that you are foreign.”

Thornton said she had been “heartened by the people who have intervened to challenge abusive behavior, condemn it and reassure victims that those views are not representative of Britain.”

News of a spike in racial abuse in the days after the referendum led to a social media campaign calling for people to wear safety pins as a sign of solidarity with the country’s immigrant population.

The idea was sparked by Twitter user Allison (@cheeahs), who wanted a simple way of showing those worried about possible attacks “my intentions to intervene and report” on their behalf.

“By all means write letters, go on marches, do everything you can,” she told CNN.

“But this is just a quiet way to show, ‘Hey it’s fine, I’m with you.’”

Others too are showing their determination to make sure race-related hate crimes do not become the norm in post-Brexit Britain: