A hate crime investigation is underway after anonymous letters threatening acid attacks were sent to Muslims in Bradford.

The letter, headed with an England flag and sword, says: “Kill Scum Muslims. Why do Muslim woman [sic] wear burkas?”

West Yorkshire Police said it was investigating reports of offensive literature sent to families in the Hanover Square area of the city.

Naz Shah, Labour MP for Bradford West, contacted police after a constituent alerted her to the letters.

She said while serious, it appeared to be a “very isolated” incident.

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The letter, sent with a second class stamp with a Lancashire postmark, says: “We are now going to do acid attacks on anyone who wears the funny black masks around your square and Bradford and other places.”

West Yorkshire Police said: “A thorough investigation has been launched and officers are working with the local community and partners to identify and prosecute those responsible for this despicable crime.

“We understand the impact hate crime and hate incidents can have on our communities and on individuals, and crimes of this nature will not be tolerated.”

Anyone with information should contact police on 101.