Controversial spit guards are to be used by police in Newham custody suites, as part of a three month trial by The Metropolitan Police.

From today mesh fabric hoods will be placed over the heads of suspects, who officers believe could bite or spit on them – to prevent the transfer of bodily fluids.

Campaign group Liberty has described the guards as cruel and degrading, but The Met says it “has a duty of care to its officers and staff”.

A statement released today says: “The issue of spitting and biting is a real problem – a particularly unpleasant form of assault, it rightly generates much concern amongst officers.

“Some of the follow-up treatment required after such an assault can be prolonged and unpleasant.”

Spit guards are already used by 22 forces across the UK, including within London by British Transport Police (BTP).

The pilot scheme has been launched following a consultation in Newham, and with The Met’s national partners.

The trial will take place in custody suites as they are controlled, supervised environments monitored by CCTV.

Afterwards the effectiveness will be gauged by The Met and the Mayor’s Office for Policing and Crime (MOPAC).