Police have been banned from pursuing criminals on mopeds or motorbikes on London’s streets because of the risk to the suspect or members of the public.

Officers have been issued with new guidance saying they must wait for a police helicopter unless there are exceptional circumstances.

The move comes as mobile phone snatches involving gangs on mopeds has soared by 31 per cent in the capital.

One victim who had his phone snatched says officers told him: “We are getting smashed over this.”

Film maker Dan Murdoch, 32, had his iPhone stolen outside his office in Camden. He told the Sun: “I’m the third person in my office this has happened to in the last few weeks.”

The new rules were issued just weeks before Henry Hicks, 18, died when he crashed his moped while being pursued by officers in Islington in December last year.

The Met’s “police driver and vehicle policy” states that police drivers should make a risk assessment when faced with a suspect who has failed to stop.

They are told to consider if the suspect is wearing a helmet, has protective clothing or has a pillion passenger.

Police helicopters should be called in whenever possible, but if one is not available the pursuit should be stopped.

The policy says drivers can only mount pursuits in rare cases such as if the rider is involved in a serious offence, or “there is clear potential for grave consequences” such as “an immediate threat to life, significant damage to property or issues of national security.”

Four police officers who were chasing Henry Hicks in two police cars when he crashed have been issued with notices warning them they are under investigation by the police watchdog.