0145 GMT March 24, 2018
West Yorkshire Police confirmed it had received six reports of letters advertising “Punish a Muslim Day”, while people in London and Birmingham said identical post had been delivered to their homes, the Independent wrote.
The letters promise “rewards” for violent acts ranging from verbal abuse of Muslims to burning or bombing mosques.
The letters also encourage people to “torture” and “butcher” Muslims in a day of Islamophobic violence on April 3.
West Yorkshire Police said it had obtained some of the letters for further analysis as the force investigates their origin.
A spokesman said: “Counter Terrorism Policing North East are coordinating the investigation at this time and will consider any potential links to existing enquiries.
“Anyone with any concerns about a communication they may have received should contact their local police force.”
A Bradford councilor was among the recipients of the letter, which he said had been posted to his business address.
“When I opened it and saw the content I was horrified,” he told the Telegraph and Argus.
“I think it has been sent out by a group with the intent of alarming people and to stir up racial hatred.
“My main concern is that it could get into the hands of other disaffected people in Bradford who just need that push to act. Some people may look at is at a sick joke. I don’t.
“I am alarmed by its content, especially where it mentions acid because of all the recent reports in the media of acid attacks.”
He said the letter was not addressed to anyone and appeared to have been “sent out randomly”. It had been stamped at a sorting office in Sheffield.
Social media users in London and Birmingham also reported receiving the letters.
A Metropolitan Police spokesperson said it was not yet clear whether any criminal allegations relating to the letters had been reported in the capital.
Iman Atta, director of anti-Muslim hate monitoring service Tell MAMA, said: “This has caused quite a lot of fear within the community.
“They are asking if they are safe, if their children are safe to play outdoors. We have told them to keep calm, and to phone the police if they receive one of these letters.”
The organization said it had received reports of the letters being sent to addresses in London, Yorkshire and the Midlands.
Last year West Yorkshire Police launched a hate crime investigation after Muslim families in Bradford were sent letters threatening acid attacks and Islamophobic murders. In a separate campaign, mosques and Islamic centers received white powder and abusive letters as part of a "structured" transatlantic campaign.