London ? Wielding submachine guns and pistols, British police are making rare armed patrols in crime-blighted London neighborhoods — a change in law enforcement tactics that may prompt calls for the wider use of weapons by the country’s traditionally unarmed Bobbies.

London’s police department said Friday that a new armed unit is carrying out regular sweeps of districts riven by gun battles between rival drug gangs.

Unlike typical police procedure, the team of about 20 officers actively seeks out criminals carrying or storing guns — rather than waiting to respond to emergency calls about incidents involving weapons.