Police are given shoot-to-kill powers in domestic violence and stalking cases

However, the decision to shoot a suspect in the head without the marksman giving a warning would only be used under exceptional circumstances, one of the country's most senior police chiefs said yesterday.

The Operation Kratos shoot-to-kill policy was adopted to deal with suicide bombers but a review has identified other types of crimes in which a firearms officer could shoot to kill without issuing any challenge. These include when an offender holding a weapon to a victim was thought to be on the brink of murder.

The use of a "shoot to kill" strategy against terrorists came under attack after police shot the innocent Brazilian Jean Charles de Menezes seven times in the head on 22 July, after mistaking him for a suicide bomber.

There has been growing criticism of the lack of accountability surrounding the police's use of the tactic. The Independent Police Complaints Commission (IPCC) is investigating the shooting, which came the day after failed bombing attempts.

Operation Kratos guidelines for dealing with suicide bombers stipulate officers under certain circumstances should aim for the head to prevent detonation of a bomb. Since the tragic error the Metropolitan Police have been reviewing and updated the tactics of Operation Kratos.

Steve House, Assistant Commissioner at the Metropolitan Police, who is carrying out the review, said: "[Kratos] was designed to deal with suicide terrorists but there are certain other circumstances where it could be applicable. For example, if there was a kidnap at gunpoint where the kidnapper was holding the victim around the body, pointing the weapon at their head and shouting they were about to shoot. Alternatively it might be a stalking case where the victim had a gun pointed at their head and there was no clear shot to the stalker's body."

He added: "You could also have a Dunblane-like situation [the Scottish town where Thomas Hamilton killed 16 children and a teacher in 1996] with a man walking around killing at will.It could be under some of these exceptional circumstances that an officer would shoot to the head without giving a warning."

He stressed that under the existing law officers are already protected if they are found to have used "reasonable force".

Mr House's review states: "It should be noted there is no legal requirement for an officer to give a verbal challenge before firing and the ACPO Police Use of Firearms manual acknowledges that there are occasions when it is not appropriate or practical."

Mr House said: "The Met have adopted this review - to wait for the completion of the IPCC inquiry is folly. We must continually refine our approach and deal with the ongoing threat."

Figures in the review strategy indicate the Metropolitan Police has had more than 1,000 reports from the public about suspected suicide bombers since 21 July, 2005. In response to these calls the police have sent out armed teams on six occasions and alerted the Kratos response teams at least 11 times. These figures do not include pre-planned police operations. The force has 12 specialist firearms units trained to deal with suspected bombers and other gunmen.

The review, part of which will be published at the Metropolitan Police Authority on Thursday, also gives details of the outline tactics used in Operation Kratos. It says there are three separate plans to deal with suicide bombers.

Operation Andromeda is designed to deal with the spontaneous sighting by a member of the public of a suspected suicide bomber.

Operation Beach is used when there is an intelligence-led covert operation to locate and arrest a suspected terrorist, while Operation Clydesdale is where intelligence has been received about a suicide attack on a pre-planned event.

The review says: "The options for all three operations range from an unarmed stop of the suspect by uniformed officers, through to the deployment of armed police officers."