Counter-terror police have arrested a man in connection with letters which urged people to "Punish a Muslim" earlier this year.
Counter Terrorism Policing North East officials supported by Lincolnshire Police arrested a 35-year-old man from South Lincoln in connection with an ongoing investigation into offensive communications.
He has been taken to a police station in West Yorkshire for questioning.
He has been arrested on suspicion of:
- Sending a hoax noxious substance under section 114(1)(a) and (3) of the Anti-Terrorism, Crime and Security Act 2001
- Sending letters/communications/articles conveying a threatening message contrary to section 1(1)(a) and (4) Malicious Communications Act 1988
- Conspiring and soliciting to commit murder contrary to section 4 of the Offences Against the Person Act 1861.
Searches have taken place at a home in South Lincoln and an office building in the city centre.
A spokesperson 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."
During the early stage of the investigation in March, Detective Chief Superintendent Martin Snowden, Head of Counter Terrorism Policing North East, said: "We take religious hatred extremely seriously and my officers will be carrying out a full and thorough investigation in response to these reports.
"These letters seek to cause fear and offence among our Muslim communities. They also seek to divide us. Yet in spite of this our communities have shown strength in their response to such hatred and in their support for each other."
The letters were circulated around various locations in the UK in March, include places in West Yorkshire.