Thousands of right-wing Pakistani activists led by cricketer-turned-politician Imran Khan on Saturday staged a protest against US drone strikes, threatening to block NATO supply routes if strikes continue.

The activists burned US flags as a mark of protest, said an AFP reporter at the scene in Peshawar, where the rally took place.

A senior police official in Peshawar told AFP that some 15,000 activists participated.

The rally was jointly organised by Khan's Pakistan Tehreek-e-Insaaf (PTI) party, together Islamic party Jamaat-e-Islami and local party Awami Jamhoori Itehad.

The three form a coalition government headed by PTI in northwestern Khyber Pakhtunkhwa province.

Khan called for a complete blockade of NATO convoys to Afghanistan to put pressure on the US to abandon its drone programme.

"We will not allow NATO supplies to pass from Khyber Pakhtunkhwa and in any case will stop drone strikes," Khan told the gathering.

NATO supplies were suspended Saturday because of the rally, which was held on same route used by NATO trucks.

A local government official said that it would not have a major effect on supplies as they were typically fewer at the weekend.

Khan accuses the United States of using a drone strike to kill Taliban chief Hakimullah Mehsud as part of an effort to sabotage potential peace talks in Pakistan.

Mehsud was killed in a drone attack in the North Waziristan tribal area on November 2, sparking outrage in the country.

The Pakistani government said the killing destroyed progress towards talks to end the Taliban's bloody six-year insurgency that has left thousands of soldiers, police and civilians dead.

On Thursday another US drone strike killed six people, including a senior leader of the ruthless Haqqani network whom the US blames for some of the deadliest attacks in neighbouring Afghanistan.

That attack hit a religious seminary in Hangu district of Khyber Pakhtunkhwa, which comes under the jurisdiction of Khan's PTI provincial government.

The drone strikes are deeply unpopular in Pakistan, and Islamabad publicly condemns them as counter-productive and a violation of sovereignty, although previous governments have given their tacit support to them.

The US regards the strikes as a highly effective tool in the fight against Islamist militancy.

Khan earlier set a November 20 deadline for the halting of drone strikes and threatened to block NATO convoys in northwestern Khyber Pakhtunkhwa, where PTI leads the coalition government.

But on Saturday he said he will take the issue to the country's top court and, if necessary, to the international court of justice.

Pakistan is a key transit route for the US-led mission in landlocked Afghanistan, particularly as NATO forces withdraw by the end of next year.

Many of the trucks now are actually removing NATO equipment after 12 years of war.

Highways used by NATO supply trucks lie with the federal government, headed by Prime Minister Nawaz Sharif.

But analysts say Sharif's ability to issue demands to Washington is constrained by the fact the US last month agreed to release around $1.6 billion in aid to Pakistan.

In addition, Pakistan has just embarked on a new $6.7 billion International Monetary Fund loan package with support from Washington.