Pakistan said Monday talks with the United States on reopening ground supply routes to international troops in neighboring Afghanistan are progressing well, indicating that Islamabad could lift the nearly six-month blockade ahead of next week's NATO summit on Afghanistan.

Pakistan shut down the supply lines after U.S. air strikes mistakenly killed 24 Pakistani troops near the Afghan border last November. The incident plunged U.S.-Pakistani ties into a diplomatic deadlock and led to the suspension of Pakistan's counter-insurgency cooperation with NATO in Afghanistan.

Foreign Minister Hina Rabbani Khar said Pakistan needs closure on the cross-border attack. She said it was important to make a point and that “Pakistan has made the point and we now need to move on and go into a positive zone of trying to conduct our relations” with the United States. But she dismissed suggestions that Pakistan is undermining the anti-terror campaign in Afghanistan by keeping its border for NATO convoys closed.

Pakistan's Prime Minister Yousuf Raza Gilani said Monday his government was in serious discussions with U.S. officials on reopening the supply routes and that talks have been “very constructive” and would “yield results.”

Pakistan's military and civilian leadership are to meet Tuesday on the issue.

After the deadly NATO air strike, already tense U.S.-Pakistani ties plunged into a diplomatic deadlock. Pakistani officials demanded an unconditional apology. But Washington refused and Islamabad retaliated by cutting off NATO ground supply routes to international forces in Afghanistan. In return, the U.S. withdrew as much as $3 billion of promised military aid.

The attack also prompted Pakistan's parliament to review its future engagement with the United States, including an end to the U.S. drone strikes. Washington says the strikes are crucial to defeating al-Qaida and the Taliban.

A reopening of supply routes could pave the way for Pakistan to attend the NATO summit in Chicago on May 20 and 21 that will focus on the future of Afghanistan after coalition combat troops leave in 2014. The move could also free up more than a $1 billion in U.S. military aid.