Pakistani Prime Minister Nawaz Sharif has urged the US to end drone attacks as Amnesty International warned that civilian-killing strikes could constitute war crimes.
Sharif, who will meet President Barack Obama on Wednesday, called for warmer ties with the US and offered Pakistan's assistance in Afghanistan as US forces prepare to withdraw next year.
But Sharif said that the unmanned strikes - which penetrate extremist havens deep in Pakistan's most lawless areas - represented a "major irritant" in relations.
"I would therefore stress the need for an end to drone attacks," Sharif said at the US Institute of Peace.
Sharif said Pakistan's political parties believed that drones violated the country's territorial integrity as well as its own efforts to fight extremism.
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The Obama adminstration has reduced the pace of drone strikes in Pakistan in light of the uproar, but US officials argue that such attacks are a useful tool against extremists and are precise enough to avoid most civilian casualties.
But Amnesty International documented cases in which it said that civilians were clearly killed, including an October 2012 strike that blew to pieces a 68-year-old grandmother as she was picking vegetables.
The human rights group said that Pakistani authorities, despite their public fuming at drone strikes, may quietly cooperate.
"We are concerned that the Pakistani authorities, or aspects of the institutions, may also be assisting the US to carry out drone attacks that may constitute human rights violations," researcher Mustafa Qadri told a news conference in Washington.
