KARACHI (AFP) - Gunmen on Saturday killed a Pakistani woman politician from cricket star Imran Khan's Movement for Justice (PTI) party in the southern port city of Karachi on the eve of partial election re-polling.

Zohra Hussain, 59, the vice president of PTI women's wing in the southern Sindh province, was targeted by three gunmen on a motorcycle outside her residence in the city's upmarket Defence neighbourhood.

The Pakistan Election Commission has ordered re-polling on Sunday at 43 polling stations in Karachi after allegations of vote-rigging in the May 11 polls which marked the first democratic transition of power in Pakistan.

PTI and the right-wing Jamaat-e-Islami party have staged nationwide protests against the alleged rigging.

Ms Hussain "was leaving her home for some work when three gunmen attacked her.

She thought they wanted to snatch her purse and handed it over to them but they killed her", Firdous Shamim, a local PTI leader, told AFP.

Police said all three gunmen escaped after the attack late Saturday.

"They shot her with one bullet near her chin and she could not survive," senior police official Nasir Aftab told AFP.

There was no immediate claim of responsibility for the attack. Tensions are running high between PTI and Karachi's dominant Muttahida Qaumi Movement (MQM) party after Khan's party accused the MQM of widespread rigging.

MQM has denied the charge and announced a boycott of the re-election.

Last weekend's election saw about 50 million Pakistanis vote, with centre-right former prime minister Nawaz Sharif emerging the winner nearly 14 years after he was deposed in a coup.

The Taleban, who denounce democracy as un-Islamic, killed more than 150 people during the election campaign, including 24 on polling day.