(Changes dateline; Adds quotes from U.S. defence officials)
By David Alexander
ISLAMABAD, Dec 9 (Reuters) - Pakistani Prime Minister Nawaz Sharif and U.S. Defense Secretary Chuck Hagel had a frank exchange on Monday about U.S. drone strikes against militants in remote areas of Pakistan, in the first visit by a Pentagon chief to the South Asian ally in almost four years.
The United States has a complicated relationship with Pakistan and ties have been further soured by a dispute over unmanned military aircraft the United States uses to target militants in Pakistan's tribal areas on the Afghan border.
Islamabad says drone strikes kill too many civilians and violate its sovereignty. Protests by anti-drone activists prompted the United States to suspend ground shipments of NATO cargo leaving Afghanistan via Pakistan last week.
Both sides were tight-lipped on the details of the talks between Hagel, Sharif and other senior Pakistani leaders, including newly appointed army chief Raheel Sharif.
"The prime minister ... conveyed Pakistan's deep concern over continuing U.S. drone strikes, stressing that drone strikes were counterproductive to our efforts to combat terrorism and extremism on an enduring basis," the foreign ministry said in a statement.
Senior U.S. defence officials, asked about the discussions on drone use, said the two leaders had a very amicable talk about counterterrorism tactics and agreed they needed to work more closely together moving forward.
"Look, there are some differences there. Bottom line it was a frank exchange between both the secretary and the prime minister and the clear resolution to continue to move forward working with one another," one defence official said.
The official, who spoke on condition of anonymity, said the overall meeting between the two leaders, who had met four times previously, was "very positive, very warm and engaging."
Hagel is the first defence minister to visit Pakistan since the U.S. raid in the city of Abbottabad that killed al Qaeda leader Osama bin Laden in 2011. Pakistan was embarrassed and angered by the surprise raid.
Hagel asked the prime minister for help in resuming the shipment of equipment from Afghanistan to the Pakistani port of Karachi across land routes known as the Pakistani ground lines of communication, or GLOCs.
While the main border crossings between Afghanistan and Pakistan are open, the United States has suspended shipments through Torkham Gate near the Khyber Pass because of concerns about driver safety as a result of anti-drone protests.
Hagel said the United States wanted to see traffic moving through the gates. A senior defence official said Hagel advised the prime minister that the issue needed to be resolved to "pre-empt what could become a much more difficult or turbulent conversation down the line."
The official said Hagel noted that failure to get shipments moving through the gates soon could disrupt efforts to ensure timely U.S. payment of Coalition Support Funds, reimbursements received by Pakistan for assistance provided to the coalition involved in the Afghan war effort.
The official said the connection Hagel made was not a threat but an expression of what could happen in the highly politicized environment in Washington.
The GLOCs are being used by the Pentagon as a primary route for withdrawing U.S. and coalition equipment as they draw down foreign forces in Afghanistan and hand over security control to Afghan troops.
Prior to the talks, a defence official said Hagel would "express appreciation that ... the government of Pakistan has made it a priority to keep the GLOCs open".
The official praised operations by Pakistani forces in a dangerous region this year against militants who posed a threat to the Torkham-Peshawar road, which serves as part of the route between Afghanistan and the Pakistani port city of Karachi.
"That's an example of the kind of effort that the Pakistan government as a whole has taken to ensure that the GLOCs stay open," the official said.
Pakistan is one of the largest recipients of U.S. foreign assistance and has received more than $16 billion in security aid since 2002, a defence official said.
The Obama administration has sought $305 million in military aid for 2014 and $858 million in a range of civilian assistance for Pakistan. (Reporting by David Alexander; Editing by Eric Beech)