More than 100 national and provincial legislators staged a protest on Thursday in the Pakistani capital Islamabad against US drone strikes on suspected militants in the country's tribal belt.

"We will continue our protest against drone strikes and...we will not allow NATO supplies to pass through the (Khyber-Pakhtunkhwa) province," former cricket star Imran Khan told the gathering outside parliament.

Khan's Pakistan Tehreek-e-Insaaf (PTI) party rules the northwestern province bordering Afghanistan. Rallies against the drone attacks began in the region's main city of Peshawar on November 24.

Apart from PTI legislators, members of parliament from the Jamaat-e-Islami party took part in the rally, shouting slogans against the United States and the Pakistan government of Prime Minister Nawaz Sharif.

Khan accused Sharif's government of double standards on the issue and called for the blocking of supply routes through Pakistan for NATO troops in Afghanistan.

"Our rulers have double standards, they say one thing to the Americans and the complete opposite to the nation," he said.

"These missile strikes violate international laws. We do not want a war with America but we are protesting against the cruel policies of America."

Activists in northwest Pakistan, some armed with clubs, have been forcibly searching trucks since late November to try to halt NATO supplies, following Khan's earlier calls to block routes.

In response the US military has suspended shipments of equipment out of Afghanistan through the Torkham border crossing in Khyber Pakhtunkhwa.

Torkham is a key transit point used by the Americans and NATO to withdraw military hardware from Afghanistan, as part of a troop pullout set to end next year.

US officials said trucks have been told to wait for now in holding areas in Afghanistan, with Washington expecting the route to resume operating soon.

Islamabad signed a deal with the US in July last year allowing NATO convoys to transit Pakistan until the end of 2015. But a spokesman for Pakistan's interior ministry said they were unable to intervene in the issue.