Unknown assailants attacked the motorcade of Pakistani Prime Minister Syed Yousaf Raza Gillani on the Islamabad Highway Wednesday afternoon, a statement released by the Prime Minister's House said.

A frame grab taken from Pakistan TV shows cracks in a window of the car of Pakistani Prime Minister Yousaf Raza Gilani's motorcade in Islamabad September 3, 2008. [Xinhua/AFP Photo]

"Of the multiple sniper shots fired on the Prime Minister's vehicle, two hit the window on the driver side. However, because of the robust and comprehensive security measures, the Prime Minister and all the members of his motorcade remained unharmed," said the statement.

The statement said a high-level inquiry had been initiated into the matter and all the law enforcement agencies were collaborating to work on the case and apprehend the culprits.

The footage aired by local TV channels showed that two bullets hit the window on the driver's side.

The private Express News quoted Interior Secretary Syed Kamal Shah as saying that Gillani was not in the car when it came under attack. Information Minister Sherry Rehman also confirmed the car was heading to the airport to fetch the Prime Minister, who was returning from Lahore, capital city of the eastern Punjab province.

Gillani had gone to Lahore to campaign for Pakistan People's Party's presidential candidate Asif Ali Zardari.

The News Network International news agency quoted Sherry Rehman as saying that Gillani returned to his official residence on another route.