Police in south-east England have arrested six teenagers over the brutal killing of a Polish man, a crime believed to be a racist attack.

Forty-year old Arkadiusz Jóźwik was severely beaten outside a pizza parlour in Harlow, Essex, on Saturday after he was heard speaking in his native Polish to a friend. He later died of his injuries.

The man he was with, a 43-year-old Pole, was hospitalised.

“He was standing eating pizza and they picked on him because of that. He does not speak much English. The young teenagers are so aggressive,” Jóźwik’s brother was quoted by the Guardian daily as saying. “After the Brexit vote it has got worse – I have seen people change – it is hard at the moment.”

Local police said that they arrested five 15-year-old boys and one 16-year-old in connection with the case, which is being treated as a murder investigation.

Following the UK’s decision to leave the EU, the number of hate crimes in Britain has been on the increase.

The home of a Polish family was burnt down in a suspected arson attack, while laminated cards reading “Go home, Polish scum” and “No more Polish Vermin” were delivered to local members of the Polish community in the town of Huntington, south-east England.