Led by Imran Kham, hundreds of demonstrators have begun a march into northwest Pakistan to protest against US drone strikes.
The former cricketer, who now heads the Pakistan Tehrik-e-Insaf (PTI) party, set off from Islamabad on Saturday, Pakistan's Dawn newspaper reported.
Dawn said he had more than a thousand people with him, though the BBC put the number in the low hundreds.
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The protesters are headed for the town of Kotkai in South Waziristan, an area that, along with neighboring North Waziristan, has been targeted by scores of US drone strikes.
The semi-autonomous tribal region is considered a stronghold for Pakistani Taliban and Al Qaeda fighters.
Regional authorities have said they have not given permission for the rally and cannot guarantee participants' security, the BBC reported. Border officials indicated that they would stop the marchers before they reached tribal areas.
Alongside Pakistani protesters, some 80 foreign activists are also taking part. They include 35 American women from the anti-war group Code Pink, according to the Guardian.
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Khan and his supporters say that drone strikes violate Pakistan's sovereignty as well as killing and traumatising civilians.
"It's totally counterproductive," the BBC quoted him as saying Saturday. "All it does is it helps the militants to recruit poor people. Clearly if they were succeeding, these drone attacks, we would be winning the war. But there's a stalemate."
He accuses President Asif Ali Zardari's government of tacit complicity in the strikes by failing to take action to end them, for example by involving the United Nations.
The PTI has made opposing drones a central part of its policy ahead of Pakistan's general election next year, according to the Daily Times.