A white supremacist has admitted sending Punish a Muslim Day letters to the Queen, Theresa May and Tory peer Lord Ahmad after some were intercepted in Sheffield.
David Parnham, 35, pleaded guilty to 15 offences relating to hundreds of letters penned between June 2016 and June 2018.
At the Old Bailey, he pleaded guilty to encouraging murder, making hoaxes involving noxious substances and bombs, sending letters with intent to cause distress and encouraging offences.
According to a case summary, seven letters were intercepted at Sheffield mail centre in July 2016 and found to contain harmless white powder.
A further eleven letters were identified as having been delivered.
A letter to David Cameron contained the wording "Allah is great" while the letters to MPs and Mosques contained racist language.
In October 2016, more letters containing white powder stated that "the clowns R coming 4 you" and were intended to reach the Queen and Theresa May.
In December 2016, Parnham sent a fan letter to Dylann Roof, a white supremacist responsible for shooting dead nine black parishioners in Charleston, South Carolina.
He told Roof: "I just wanted to thank you for opening my eyes. Ever since you carried out what I'd call the 'cleansing' I've felt differently about what you'd call 'racial awareness'."
In February 2007, letters were sent to various Mosques and Islamic centres around the county.
A letter to Berkeley Street Mosque in Hull contained a drawing of a sword with a swastika on it cutting someone's head off with the words "you are going to be slaughtered very soon".
In March 2017, letters were sent to addresses around University of Sheffield campus calling for the extermination of minority racial and religious groups.
They contained suggestions on how to kill people and an offer to make a donation of £100 to charity for each death.
In 2018, a series of typed "Punish a Muslim day" letters were sent out to a large number of people, encouraging violence on the April 3 2018 - Roof's birthday.
Parnham was snared through DNA, handwriting and fingerprints on the letters.
When he was arrested in June 2018, he refused to answer any questions.
Following his guilty pleas, Parnham, of St Andrew's Close in Lincoln, was remanded into custody by Judge Anthony Leonard QC.
He will be sentenced at a later date after the completion of reports.