PESHAWAR, Pakistan -- Thousands of people protesting U.S. drone strikes blocked a road in northwest Pakistan on Saturday used to truck NATO troop supplies and equipment in and out of Afghanistan, the latest sign of rising tension caused by the attacks.

The protest, which was led by Pakistani politician and cricket star Imran Khan, likely had more symbolic value than practical impact because there is normally little NATO supply traffic on the road on Saturdays. The blocked route in Khyber Pakhtunkhwa province leads to one of two border crossings used to send supplies overland from Pakistan to neighbouring Afghanistan.

Khan, whose Tehreek-e-Insaf party runs the Khyber Pakhtunkhwa government, called on federal officials to take a firmer stance to force the U.S. to end drone attacks and block NATO supplies across the country.

"We will put pressure on America, and our protest will continue if drone attacks are not stopped," Khan told the protesters, who dispersed after his speech.

The U.S. Embassy in Islamabad declined to comment on the protest. The U.S. leads the coalition of NATO troops battling the Taliban in Afghanistan.

Drone strikes have been a growing source of friction between Islamabad and Washington. Khan and other officials regularly denounce the attacks as a violation of Pakistan's sovereignty, although the country's government is known to have supported some of the strikes in the past. The tension has further complicated a relationship that Washington views as vital to fight al-Qaida and the Taliban, as well as negotiate peace in Afghanistan.

The protest comes only two days after a rare U.S. drone strike outside of Pakistan's remote tribal region killed five people, including at least three Afghan militants, at an Islamic seminary in Khyber Pakhtunkhwa.

The attack outraged Pakistani officials, as did one on Nov. 1 that killed the former leader of the Pakistani Taliban, Hakimullah Mehsud, a day before the Pakistani government said it was going to invite him to hold peace talks.

Khan pushed the Pakistani government block NATO supplies after the strike on Mehsud, but it has shown little interest in doing so. Pakistani Prime Minister Nawaz Sharif has been a vocal critic of drone strikes, but he has also said he values the country's relationship with the U.S.

Sharif pushed President Barack Obama to end drone strikes in a visit to Washington in October, but the U.S. government has shown no indication that it intends to stop using a tool that it sees as vital to battling al Qaeda and the Taliban.

When Khan failed to persuade the Pakistani government to block NATO supplies earlier this month, he announced that he would hold a protest to do so himself.

Around 10,000 people participated in Saturday's protest, which blocked a road that leads to the Torkham border crossing in Pakistan's Khyber tribal area. The protesters included members of Khan's party and two other parties that are coalition partners in the Khyber Pakhtunkhwa government. They shouted anti-U.S. slogans, such as "Down with America" and "Stop drone attacks."

"I am participating in today's sit-in to convey a message to America that we hate them since they are killing our people in drone attacks," said Hussain Shah, a 21-year-old university student. "America must stop drone attacks for peace in our country."

The federal information minister, Pervez Rashid, said the federal government's anti-drone stance was clear and accused Khan of "playing politics" on the issue.

Drone strikes are widely unpopular with Pakistan's public, both because they are seen as violating the nation's sovereignty and are believed to kill too many innocent civilians. Human rights organizations have said hundreds of civilians have died in the attacks, although the U.S. insists the number is much lower.

There is normally little NATO supply traffic on Saturdays on the road that the protesters blocked, said Tahir Khan, a government official at Torkham. Most trucks try to arrive at the border by Friday evening so they can clear customs the following morning, he said. The crossing is closed to trucks carrying NATO supplies on Sunday.

The land routes through Pakistan from the southern port city of Karachi to Torkham and another border crossing in southwest Baluchistan province have been key to getting supplies to NATO troops in Afghanistan for the course of most of the war there. They are now increasingly being used to ship equipment out of Afghanistan as the U.S. seeks to withdraw most of its combat troops from the country by the end of 2014.

The routes have not been immune to the often turbulent relationship between Pakistan and the U.S. in the past. The Pakistani government blocked the routes for over seven months following U.S. airstrikes that accidentally killed two dozen soldiers on the Afghan border in November 2011. Pakistan finally reopened the routes after the U.S. apologized for the deaths of the Pakistani troops.

Also Saturday, militants kidnapped four school teachers who were working on a polio vaccination drive in Khyber's Sipah village, said local government official Khurshid Khan. Negotiations are underway for their release, he said.

Militants have killed over a dozen polio workers and police protecting them over the last year. They claim the workers are spies and the vaccination is meant to make Muslim children sterile.