Three people, including a policeman, have been arrested on suspicion of conspiracy to pervert the course of justice after giving "false and malicious information" about a plot to kidnap and kill an on-duty officer.

West Midlands Police said the men have been arrested following an investigation over the "anonymous but credible" call to police detailing an alleged plot to kidnap and kill a serving officer in December 2014.

A major security alert at a was triggered resulting in all officers being held on duty while they were briefed about the threat and a 31-year-old man being arrested on suspicion of threatening to kill police officers.

However, the 31-year-old was eliminated from police enquiries after investigators ruled the call to West Midlands Police was not terrorist-related, that there was never "any credible threat of a kidnap" and that the call was a hoax.

Three men, aged 25, 28 and 31, all from the Birmingham area, have now been arrested. The 28-year-old is a serving police officer at Birmingham West and Central Local Policing Unit. He has also been arrested on suspicion of misconduct in a public office and misuse of police systems. The other two suspects have also been arrested on suspicion of conspiracy to commit misconduct in a public office.

The three men are being questioned by detectives from West Midland Police's Anti-Corruption Unit, with support from the Counter Terrorism Unit.

A West Midlands Police spokesperson said: "The arrests follow an investigation into false and malicious information given to West Midlands Police on 8 December 2014, which stated that an officer was going to be kidnapped as part of a terrorist plot.

"At a time when the national threat level was severe, the threat was considered credible and police acted swiftly to protect officers and police staff. A subsequent investigation revealed that the call was false and malicious."

Elsewhere, the 31-year-old man who was eliminated from enquiries was questioned by police over immigration matters and has subsequently been deported by Border Officials.