Flyers saying “no more Polish vermin” posted in letterboxes, protesters holding signs reading “Rapefugees not welcome” and neo-Nazi stickers plastered in public places are some examples of post-referendum racism being documented on social media.

Dozens of people have taken to Twitter using the hashtag #PostRefRacism to describe scenes of anger and hatred they’ve witnessed on Britain’s streets after the Brexit vote.

Polish father & son beaten up by thug shouting for them to go home in East London last night https://t.co/GIFUj4zaSqpic.twitter.com/QHJPSi4O6Q — I was a JSA claimant (@imajsaclaimant) June 26, 2016 Disgusting RT @fionaand: Older woman on the 134 bus gleefully telling a young Polish woman and her baby to get off and get packing.Horrific. — ChannyAmos (@Channy_Amos) June 25, 2016 Last night a Sikh radiographer colleague of mine was told by a patient "shouldn't you be on a plane back to Pakistan? we voted you out" 😞 — Dr. M. Ali Abbasi (@drmaliabbasi) June 26, 2016 Just arrived at a 78% Muslim school. White man stood making victory signs at families walking past. This is the racism we have legitimised. — Dr Karen Bateson (@KarenJBateson) June 24, 2016

Over the weekend, right-wing and left-wing protesters faced off in Newcastle as the former called for the “repatriation” of immigrants.

In Birmingham, people holding flags reading “rapefugees not welcome” shouted at worshippers outside a mosque on Sunday.

Just drove past a protest in which a man was holding up the England flag with 'rapeugees not welcome' written on it. pic.twitter.com/OfSviwzHIE — Hassan Hussain (@Hassan_Hussain_) June 25, 2016

A Facebook group set up to document the rise in racism in the UK following the Brexit vote says it is “already seeing a stark increase in racist harassment and aggression.”

“It seems that the referendum has validated and vindicated racist views; racist behaviour is now shameless in its expression. This cannot go unchallenged,” the organizers wrote.

“We must not stand by and tolerate the normalisation and mainstreaming of racism. Just because we’ve voted to leave the European Union DOES NOT mean there is a democratic mandate for racist harassment, aggression, intimidation or hate speech.”

Police say they are investigating multiple reports of hate crime.

Wiltshire Police investigating a "potentially racially-aggravated assault on a Polish woman in Salisbury on Friday" — Rupert Evelyn (@rupertevelyn) June 27, 2016 Not all Brexiters are racists but all racists are emboldened by #Brexit.Our task now is to counter the #PostRefRacism & xenophobia unleashed — Mandy Vere (@nfnmandy) June 26, 2016 It is up to all of us to fight #PostRefRacism. Do not let ignorance and hatred go unchallenged. Take your country back from the bigots. — Richard GodwIN (@richardjgodwin) June 26, 2016

MPs, including outgoing Prime Minister David Cameron, took the opportunity on Monday afternoon in Parliament to condemn the post-Brexit racism.