An opposition party worker was shot dead in Pakistan on Monday, officials said, as hundreds of activists clashed with riot police armed with water cannon in the central city of Faisalabad.

The opposition Pakistan Tehreek-e-Insaaf (Pakistan Movement for Justice or PTI) led by cricketer-turned-politician Imran Khan had vowed to paralyze the city as part of its efforts to topple the government of Prime Minister Nawaz Sharif, which it accuses of poll-rigging.

The death has the potential to spark further violence and reinvigorate Khan's movement, which had lost steam since his workers and followers of a populist cleric stormed the state broadcaster in the capital in September.

TV footage showed PTI workers clashing with supporters of Sharif as well as with riot police, who baton-charged them as parts of Faisalabad came to a standstill.

Nabeela Ghazanfar, a spokeswoman for police in Punjab province, told AFP: "One protester has been killed and five others injured including two policemen.

"The Punjab police chief has issued strict orders not to let anybody take the law into their hands."

A government spokesperson said police were searching for the shooter.

A doctor in a Faisalabad hospital confirmed the death, adding the protester died of bullet wounds.

"One of the wounded succumbed to his injuries, he had received bullet wounds," he said. "We have five wounded people receiving treatment," he continued, adding they were in stable condition.

Followers of Khan and of cleric Tahir-ul-Qadri clashed with police in late August after they tried to storm the prime minister's residence, leaving three demonstrators dead and hundreds injured on both sides.

Both groups allege that Sharif had rigged the 2013 general election that saw him sweep to power.

On September 1, the opposition groups briefly occupied the state broadcaster, raising fears the military could intervene to end the crisis as it has done in the past.

Since then the movement has lost some momentum but Khan has warned that he and his supporters will paralyze the country on December 18 if their demands are not met.