Image copyright Met Police Image caption Trials are under way on how cameras can be used in undercover operations

Armed officers are to be issued with head-mounted cameras in a effort to provide "greater transparency" in police shootings, the Met Police says.

The Met - the UK's largest police force - said officers in its armed response units will have cameras fitted to baseball caps and ballistic helmets.

It will give "a documented and accurate account" of situations, the Met added.

Armed officers had trialled body-mounted cameras, but in 2015 they were criticised as "unfit-for-purpose".

Their introduction followed criticisms of the Met over the death of Mark Duggan, who was shot by armed officers in August 2011, sparking riots across England.

However, the force said it was still examining how cameras could be used in such undercover operations.

'World's largest rollout'

The new cameras will be worn by officers who carry an "overt" firearm.

The police watchdog, the Independent Police Complaints Commission (IPCC), said during the trial the positioning of the cameras on officers' bodies had obscured and impacted on the the quality of some footage.

The Met says it has decided that because of the way armed police operate, head cameras are a better option.

The firearms command will receive around 1,000 cameras, the force added, saying it was part of "the largest rollout of body worn cameras by police in the world".

'Greater transparency'

Commander Matt Twist said armed officers "very much welcome" the cameras.

"It provides a documented and accurate account of the threats officers face and the split second decisions they make," he said.

"The cameras also offer greater transparency for those in front of the camera as well as those behind it."

Body-mounted cameras have already been issued to frontline officers in 30 of the 32 London boroughs, as well as to officers from the roads and transport units, the territorial support group and the dog unit.

The deployment of 22,000 cameras, which do not permanently record, is anticipated to be complete by the end of October, the force added.

The Mayor of London, Sadiq Khan, said cameras were "a huge step forward in bringing our capital's police force into the 21st century and building trust and confidence in the city's policing".