Pakistan Prime Minister Yousuf Raza Gilani escaped an assassination attempt on Wednesday when unidentified gunmen fired shots at his motorcade near the garrison city of Rawalpindi, officials said.

The shooting occurred shortly after Gilani was returning from an official visit to the eastern city of Lahore. His motorcade was going to Islamabad from the high-security Chaklala military airbase in Rawalpindi.

A spokesman for the Prime Minister's House said Gilani and members of his staff had escaped unhurt and were safe.

He said police had been put on high alert and an investigation launched into the incident.

The unidentified assailants fired at Gilani's motorcade on a highway. At least two shots had hit the Prime Minister's bulletproof vehicle, TV channels quoted officials as saying.

State-run PTV beamed footage of the damage caused by the bullets to the window of the driver's door of the vehicle.

No group claimed responsibility for the attack.

Reports said the incident occurred at a spot where former premier and PML-N chief Nawaz Sharif's motorcade was fired at on December 27 last year, shortly before Pakistan People's Party (PPP) chairperson Benazir Bhutto was assassinated in a suicide bombing in Rawalpindi.