At least three police officials lost their lives when unidentified assailants opened fire on their vehicle in Peshawar's Chamkani area on Thursday evening, police said.

The police personnel were on a routine patrol after iftar when three gunmen riding a motorcycle targeted the police van, Superintendent of Police (SP) rural Furqan Bilal said.

As a result of the firing, constables Umer Hayat, Shahid and Intikhab Alam laid down their lives while head constable Sheraz sustained injuries.

The police party, which belonged to Waheedabad police post, retaliated to the assailants' firing, shooting dead one of the three militants. The other two gunmen managed to flee the scene, SP Bilal said.

Nobody immediately claimed responsibility for the attack.

For decades the city of Peshawar has faced the threat of militants, due to its status as a front line for the ongoing war on terror as well as its proximity to the restless tribal areas and the Pak-Afghan border.

The number of attacks in the country has fallen around 70 per cent, due to a combination of the military offensive against Taliban bases along the Afghan border and government initiatives to tackle militancy, but attacks on security and civilian targets continue to occur occasionally.

The Pakistan Army had launched Operation Raddul Fasaad earlier this year in the aftermath of a fresh resurgence in terror attacks in the country.

The operation seeks to eliminate the "residual/latent threat of terrorism", consolidating the gains made in other military operations, and further ensuring the security of Pakistan's borders.

Hundreds of suspected terrorists have reportedly either been killed or arrested in raids carried out by security personnel since the start of the operation.