Islamabad, May 19 (IANS): Re-polling in a parliamentary seat started in Pakistan's port city Karachi Sunday following allegations of vote rigging, officials said.

The Election Commission ordered re-polling after political parties alleged that election officials had been stopped from reaching the polling centres May 11, reports Xinhua.

Voting will continue until 5 p.m. on one National Assembly and two provincial assembly seats.

Hours before the polling, gunmen shot dead a senior woman member of the Tehreek-e-Insaf party (PTI), causing tension in the city.

PTI chief Imran Khan blamed the powerful Mutahida Qaumi Movement (MQM) for the killing of Zara Shahid Hussain, 59. MQM denied the charge.

Re-polling is being held at 43 polling stations in the posh Clifton and cantonment areas of Karachi. The MQM and the Pakistan Peoples Party have boycotted the re-polling.

Security personnel including soldiers and paramilitary forces have been deployed at 44 polling stations to maintain peace.