ISLAMABAD — Dozens of American activists joined hundreds of Pakistanis Saturday on a motorcade "march" against U.S. drone strikes, hoping to reach a militant-riddled Afghan border region that has been the focus of many such attacks.

Various Pakistani Taliban factions have denounced the protest and questioned the motives of its leader, ex-cricket star-turned-politician Imran Khan, whom they dub a tool of the West. Multiple militant groups have threatened to attack the march, which is scheduled to arrive in the dangerous tribal areas on Sunday. But Khan and other participants insisted they would go as far as possible.

"This is a peace march, an effort for peace in Pakistan on our part ... We are not going to fight anyone," Khan said as he launched the motorcade, which had around 150 vehicles, from Islamabad.

Like many in Pakistan, the demonstrators allege the drone strikes kill numerous innocent civilians and terrorize peaceful communities. U.S. officials rarely discuss the top-secret program, but have insisted most of those killed in the strikes are Islamist militants.

Around three dozen Americans from the U.S.-based anti-war group CODEPINK joined Khan for the march, which is intended to finish in South Waziristan, a tribal region that has been the scene of a Pakistani army offensive and a frequent target of drone strikes.

"It feels great. I'm hoping that what it will show is that the Pakistani people and American people and even the people in the tribal areas want peace," said Joe Lombardo, a representative of the U.S. group.

Access to Pakistan's tribal regions is heavily restricted, and foreigners for the most part are forbidden from entering. It was unclear whether the Westerners participating in the anti-drone march would be allowed to cross in.

South Waziristan has theoretically been under the army's control since its late 2009 operation there, but militants still roam the area.

The main faction of the Pakistani Taliban, which is based in South Waziristan, issued a statement Saturday calling Khan a "slave of the West" and saying that the militants "don't need any sympathy" from such "a secular and liberal person."

The statement did not reveal anything about the militants' plans regarding the march, but added: "Imran Khan's so-called Peace March is not in sympathy for drone-hit Muslims. Instead, it's an attempt by him to increase his political stature."

On Sunday, a statement from a Taliban faction said to be based in Pakistan's eastern Punjab province, warned that militants would welcome the protesters with suicide bombings.

"We ask the brave people of Waziristan not to side with the gang of Jews and Christians — otherwise their fate will be terrible," the Punjabi Taliban said in the statement.

Khan said earlier in the week that South Waziristan tribal leaders had assured him that he and his entourage would be protected there.

Still, he did allude to the possibility that entering the tribal area might not be possible, saying that the marchers would go as far as they could, and stage a major rally wherever they decided to stop.