RAWALPINDI - A senior Pakistani politician has survived an attempt on his life when unidentified gunmen shot at him in the city of Rawalpindi in Punjab province.

Sheikh Rashid Ahmed, leader of one faction of the Pakistan Muslim League (PML) party, suffered from a sprained ankle, hospital staff said.

Mr Ahmed was coming out of an election meeting with when four gunmen on motorcycles shot at him.

Three of his security guards were killed in the attack, police said.

No arrests have been made in the connection with the incident, the police said.

The attack has disrupted Mr Ahmed's campaign for a key by-election which many believe will test the popularity of the opposing faction of the PML - run by former prime minister Nawaz Sharif - which rules Punjab province.

Mr Sharif's faction won the largest number of seats in the province in the 2008 elections.

But it had asked for the postponement of the by-election in view of the "fragile" law and order situation in Punjab.

However, Pakistan's Supreme Court ruled in favour of an argument put forward by Mr Ahmed to hold the election.

Mr Ahmed, who was once part of Mr Sharif's faction, is contesting the Rawalpindi constituency.

The BBC's M Ilyas Khan in Islamabad says this is the fifth attack of its kind in the Rawalpindi-Islamabad area, involving gunmen on motorcycles.

Three army officers were killed in separate gun attacks lat year. Pakistan's minister of religious affairs survived an assassination attempt.