Police say gunmen on a motorcycle have shot and killed a senior member of a leading Pakistani political party.

Police officer Sarfaraz Nawaz says Zohra Shahid was gunned down outside her home in the city of Karachi in southern Sindh province. Shahid was the vice president of former Pakistani cricket star Imran Khan's Pakistan Tehreek-e-Insaf party in Sindh.

No one has claimed responsibility for the killing.

Khan's party has claimed it was the victim of vote rigging in several areas of Pakistan, including Karachi, in national elections held on May 11. Pakistan's election commission plans to re-do the vote for several national assembly seats, including in Karachi.

A spokesman for Khan's party, Jamal Siddiqui, claimed Shahid was killed to sabotage a re-vote scheduled to be held in Karachi on Sunday.