Police arrested two teenage boys in West Hampstead on Wednesday after an officer was allegedly knocked from his bike and another was said to have been tripped and spat at.

The confrontation took place at around 2.10pm on August 5.

Plain clothes police on bikes were in the area after a spate of reported mobile phone thefts.

One teenager rode away from police, who had asked to search him, before allegedly “slowing down to cause the collision” with the police officer chasing him on his own bike.

The officer fell off his cycle and fractured his wrist.

A boy, 17, was arrested, but is then said to have “deliberately tripped up” a second officer and “spat in his face”. He was arrested for assaulting a police officer and for obstructing police.

Another 17-year-old was arrested after allegedly “verbally abusing” officers with “homophobic and dereogatory” language.

Both were released on bail.

Det Insp Eliot Porritt said: “These officers were simply out doing their job, trying to prevent crime in an area known for phone thefts when they were subject to this disgusting and vile behaviour.

“No person should be assaulted whilst at work. We will not tolerate such actions.”