A man has been charged with soliciting to murder after being accused of sending threatening 'Punish a Muslim Day' letters.
David Parnham, 35, from Lincoln in the UK, has been charged with a total of 14 offences - including staging a bomb hoax, sending threatening letters and sending a hoax noxious substance.
The anonymous notes, which offered points for a string of offences ranging from verbally abusing a Muslim to "nuking Mecca", were sent to Muslims across England and Wales in February and March.
Parnham was arrested in Lincoln on Tuesday, following searches at a home and an office building.
"Officers from the North East Counter Terrorism Unit (NECTU), supported by Lincolnshire Police, have arrested a 35-year-old man from south Lincoln in connection with an ongoing investigation into offensive communications," a police spokesman said.
"We understand that people may be concerned following this activity.
"However, we would like to reassure communities that this activity is a result of an ongoing, intelligence led investigation and was not in response to an immediate threat."
The charging of Parnham has been welcomed by Tell MAMA, which supports victims of anti-Muslim prejudice.
Tell MAMA director Iman Atta said "we warmly welcome the charging decision that has been made on 14 separate offences".
"This is a significant development in what has been a difficult period for Muslim communities who have received such letters," Mr Atta said.
"The campaigns caused anger, dismay and fear within some sections of Muslim communities, and we will do all we can to assist the police and counter-terrorism officers."
Parnham appeared at Westminster Magistrates Court on Friday and was remanded. He is due to appear at the Old Bailey on June 29.