Currently, Washington uses Pakistan's airspace to reach Afghanistan for ongoing intelligence-gathering efforts

The US administration on Friday informed lawmakers that the country is nearing a formalise an agreement with Pakistan for use of its airspace to conduct military and intelligence operations in Afghanistan, CNN reported citing three sources familiar with the details of the classified briefing with members of Congress.

Islamabad has expressed a desire to sign a Memorandum of Understanding (MOU) in exchange for assistance with its own counterterrorism efforts, one of the sources said. But the negotiations are ongoing, another source told CNN, and the terms of the agreement, which has not been finalised, could still change.

An agreement was discussed when US officials visited Pakistan, the third source told CNN, adding but it is not yet clear what Pakistan wants or how much the US would be willing to give in return.

Currently, Washington uses Pakistan's airspace to reach Afghanistan for ongoing intelligence-gathering efforts.

But so far there's no formal agreement in place that can ensure continued access to a critical piece of airspace necessary for the US to reach Afghanistan.

The air corridor through Pakistan to Afghanistan may become even more critical if and when the US resumes flights into Kabul to fly out American citizens and others who remain in the country.

The US -- without any formal agreement in place-- runs the risk of Pakistan refusing entry to its military aircraft and drones en route to Afghanistan.