Gunmen attacked an election rally in Pakistan's southern Punjab province on Thursday and abducted the son of a former prime minister, intensifying what has already been a violent run-up to Saturday's national elections.

Ali Haider Gilani, the son of ex-premier Yousuf Raza Gilani from the Pakistan People's Party, is running for a provincial assembly seat in the district of Multan. He was attending an election event in the city of Multan on Thursday - the last day of campaigning across Pakistan - when gunmen pulled up, started shooting, threw him into a vehicle and drove off, officials and witnesses said.

"If we don't get my brother by this evening I will not let the elections happen in my area," said his brother Musa.

It was not immediately known who abducted Gilani or why.

Taliban spokesman Ihsanullah Ihsan denied responsibility in a telephone call to Reuters.

A resident of Multan who attended the rally told a local TV station that the attackers first pulled up in a car and motorcycle outside the venue where the younger Gilani was meeting with a few hundred supporters.

When he came out of the building, two gunmen opened fire, killing at least one of the people in Gilani's entourage.

"One of the gunmen grabbed Haider who had blood splashed on his trousers," said Shehryar Ali in comments aired by Pakistani broadcaster Geo News.

The former prime minister was not at the event when his son was taken.

Speaking in Islamabad to reporters, the elder Gilani appeared shaken but composed. He said two of his son's guards were killed in the attack, but he did not know whether his son was wounded.

"His two guards were shielding him, and they died," said the former premier in comments aired on Pakistani television. "I urge all of my party supporters to remain peaceful and participate in the vote."

Gilani's father served for about four years as prime minister but was forced out of office last summer by the Supreme Court after refusing to pursue a corruption case against President Asif Ali Zardari.

Saturday's election marks a milestone for Pakistan as a civilian government completes its term and prepares to hand off to another.

But the race has been marred by violent attacks against candidates and at election events.

Much of the violence has been at the hands of the Taliban, who have mainly targeted political parties that have supported military operations against the militants in northwestern Pakistan.

The younger Gilani is running as a candidate for the PPP, one of the three parties the Taliban has said it is focusing on.

The party is the incumbent in this election but the security threats have forced it to curtail its campaign activities. Instead of the large, outdoor rallies that the party used to rally thousands of voters in the past, they have been relying on television and newspaper advertisements and smaller, indoor meetings with supporters.

Party officials have complained that a lack of protection means they have been left vulnerable.

"We were screaming that we need security for our candidates. We were saying that we have received threats, but no one heard our pleas, and we did not get security," said a party spokeswoman, Sharmila Farouqi. "Now see what has happened. The son of a former prime minister has been kidnapped."

AP-Reuters