Kenyan police have arrested a 19-year-old motorist who was filmed beating up a traffic policeman on a road in the capital, Nairobi.

In a video that has been widely shared, the man is seen attacking the policeman with punches and kicks to the head even after the officer falls to the ground.

The motorist escaped after other people intervened to help the officer.

The shocking attack has led to a rare outpouring of sympathy for the police, who have a reputation for brutality and bribery.

A police report said the man was initially stopped after he made a U-turn on a busy road, obstructing other motorists.

It said that the traffic officer, Patrick Ogendo, entered the vehicle and instructed him to drive to a nearby police station.

While on the way, “the driver suddenly stopped and drew a sword under the seat”.

“The officer jumped out of the vehicle for his safety and the driver followed him with blows and kicks," the statement added.

It said the driver also made away with a police pocket phone battery.

The policeman received first aid at a nearby health centre and was transferred to a hospital for treatment.

An alleged accomplice of the suspect was arrested at the scene and a police team was mobilised to search for the man who carried out the attack, the statement said.

The attack has been widely condemned, with some describing the attack as unacceptable.

“How do you assault a uniformed police officer in this manner?" asked Robert Alai, a member of Nairobi's county assembly.

“This is totally unacceptable. We shouldn't allow our police officers in uniform to be humiliated to this level," said Mike Sonko, a former Nairobi governor.

The suspect was reportedly arrested at his residence in the capital later on Sunday evening.

Nairobi head of traffic Vitalis Otieno told local media that he would be charged with a number of offences including attempted murder.