Police in London say tough tactics used against suspected violent thieves on mopeds, including chasing them and knocking them off their bikes, have helped reduce crime.

The Metropolitan police said there had been a 36% reduction in thefts that involved mopeds or scooters since the tactics were adopted last year.

These include providing officers with a special marking spray to fire at suspects, using remote-controlled spikes to burst the tyres of bikes, and using police cars to knock suspects off their bikes.

Officers had been reluctant to chase mopeds, some driven at high speed by suspects as young as 14, amid fears of injury or death.

But Insp Jim Corbett said those who thought they would not be chased if they took off their helmets were in for a surprise: “A big myth that we have is that if people remove their helmets they think they are not going to be pursued.”

He said officers were told by one person they caught: “I took my helmet off as I thought you would stop chasing me.” That person, who was later jailed, rode on to the pavement. Officers deemed him a danger to the public and used “tactical contact” to knock him off his scooter.

A special team called Scorpion drivers have been trained in tactical contact. Policies were drawn up using legal experts to minimise the chances of officers being prosecuted for using the technique, which was introduced in October 2017. So far this year officers have knocked suspects off their mopeds or scooters 63 times, including those who have taken off their helmets.

One Scorpion driver, Sgt Tony McGovern, said it was one of the hardest tactics to use: “It’s just a slight nudge. It’s controlled.” He said suspects were amazed when in some cases they were sent sprawling off their mopeds. “They are shocked. They say ‘We did not think you were allowed to do that,’ especially when they take off their helmet. They are confused.”

He said other police cars would try to slow the scooter or moped before he and other specialist drivers struck the suspect’s vehicle at “as slow a speed as possible”.

McGovern said Scorpion drivers aimed to minimise injury to those being pursued and civilians. At impact the driver removes her or his foot from the accelerator and uses the brakes to nudge the suspect off the bike, he said. “It’s incredibly quick and very dynamic. Your decision-making changes in a split second.”

Three incidents have been referred to the police watchdog for investigation.

The Met said last year 24% of their pursuits involved officers chasing mopeds or scooters. This year, that figure rose to 40%.

The issue of moped crime has been seen as part of a crimewave that made headlines and added to public unease about the prevalence of violence.

Hailing a fall in crime in which mopeds were used, the Met said from January to October 2017 there were 19,455 offences in London. From January this year to October there were 12,419.

Commander Amanda Pearson said: “The public quite rightly expects us to intervene to keep London safe. Our highly trained police drivers weigh up the risks and decide upon the most appropriate tactics in those circumstances.

“Offenders on mopeds and motorcycles who attempt to evade the police are making a choice that puts themselves and others at risk. A lot of them get up and run away, looking aghast at how dare we.”

Several factors triggered the surge in moped crime from early 2017. One was an increase in moped and scooter ownership, coupled with security measures not being tough enough to stop them being stolen.

Smartphones are lucrative gadgets for thieves, and the Met had previously said Apple iPhones were the target in two-thirds of thefts, followed by Samsung Galaxies. Young people behind the thefts can make up to £200 for each phone they steal.

The crimewave is being driven by a growing illegal market in phone parts, with some young people stealing brands of mobiles to order. There have been signs that some of the offending is highly organised.

Initially Met chiefs believed moped-riding thieves tended to drive by at speed before snatching a phone from a victim’s hand. But an increase in the levels of violence used led police chiefs to develop tougher tactics.