France's Prime Minister vowed "unrelenting" punishments for rioters that attacked a police car and set it on fire in Paris during an authorised protest against police violence. Authorities opened an investigation for attempted homicide and arrested five people over the shocking incident that was captured on camera.

Two officers, a man and a woman, were slightly injured as their vehicle came under attack by a mob as it proceeded slowly in a trafficked street of the 10th arrondissement on 18 May. Footage captured by onlookers shows a masked protester breaking the driver's window with a kick before another assailant starts bashing the vehicle with an iron bar. A third man then smashes the rear glass and an inflammable device is thrown inside.

After a short confrontation with one attacker the policemen abandon the car which later catches becoming engulfed by flames. "The rule of law is our most valuable asset and the sanctions must be unrelenting," Prime Minister Manuel Valls told RTL radio, adding that the rioters wanted "to kill a cop".

The incident took place as policemen across France took to the streets to voice their discomfort at what they lamented was the increasingly hateful attitude towards security forces. The assailants were instead taking part to an unauthorised counter-demonstration in Paris purportedly denouncing police excessive use of force.

A debate on police methods and violent demonstrations was ignited by recent demonstrations against a controversial labour reform where protesters accused authorities of instigating disorders.