Three men, including a police officer, have been arrested following a hoax terror plot to kidnap an officer.
The West Midlands officer and two other men are being questioned on suspicion of conspiracy to pervert the course of justice.
Police said they were given "false and malicious information" suggesting an officer was to "be kidnapped as part of a terrorist plot".
West Midlands police were put on high alert because of the hoax.
The three Birmingham men are being questioned by anti-terrorism and anti-corruption teams.
The 28-year-old officer at Birmingham West & Central Local Policing Unit has also been arrested on suspicion of misconduct in a public office and misuse of police systems.
The other men, aged 25 and 31, are also being questioned on suspicion of conspiracy to commit misconduct in a public office.