LONDON – A man has admitted sending hundreds of racist letters nationwide including calls for a “Punish a Muslim Day” and letters containing white powder to several Muslim parliamentarians and mosques.

“This case has affected a substantial number of victims across the country and beyond. The abusive, racist and threatening language used in the letters has caused major distress,” Detective Chief Superintendent Martin Snowden, head of Counterterrorism Policing North East, said, The Independent reported.

“Many Muslim communities strongly believed there was a real threat to their safety which understandably caused fear, offense, and worry.

“I want to reassure all communities that the police are committed to tackling all forms of toxic extremist ideology which has the potential to undermine public safety and security,” he added.

David Parnham, 35, sent the letters to mosques, Muslim parliamentarians including Lord Ahmed of Wimbledon, the Queen, David Cameron, and Theresa May.

During his two-year campaign, Parnham sent wave after wave of letters across the country that included white supremacist imagery and threats to minorities, mostly Muslims.

A letter to a mosque in Hull warned people they would be “slaughtered very soon”.

He admitted devising the “punish a Muslim day” letters that caused widespread alarm earlier this year, and suggested Muslims be “exterminated”.

One read: “Your brains will be splattered all over the walls. A good Muslim is a dead Muslim. Killin Muslims is awesome.”

Parnham was an avowed fan of white supremacist Dylann Roof, who in 2015 shot dead nine black worshippers at a church in South Carolina.

He pleaded guilty at the Old Bailey to 15 offenses, including soliciting to murder and staging a bomb hoax.

Counterterrorist experts caught him four months ago after extensive investigations including collecting his DNA and fingerprints from some of the letters.

He was remanded in custody until 23 November, when he will be sentenced.