Detectives investigating hate mail sent under the banner of “Punish a Muslim Day” have arrested a man, police said on Wednesday.
At least 20 anonymous hate letters were sent this year encouraging Britons to punish a Muslim on April 3, inciting murder or arson attacks on mosques.
Letters were sent in May with further threats and five British MPs with South Asian backgrounds also received Islamophobic hate mail, along with packages containing a harmless sticky liquid.
The man, 35, was arrested in Lincolnshire, east England, on suspicion of sending a hoax noxious substance, sending threatening letters and conspiracy to commit murder, according to a statement. Police were searching an office and home in the county.
The hate campaign triggered fear across UK cities and sparked a major police counter-terrorism investigation. In the event, April 3 passed without any specific violence targeting Muslims.
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."