Washington: The US has invited Pakistan and Afghanistan to join the investigation into the last weekend's attack by NATO combat aircraft on two Pakistani military border posts in which 24 Pakistani soldiers were killed.

Directing a probe, led by Brigadier General Stephen Clark from CENTCOM headquarters in Florida into the incident, US Central Command (CENTCOM) Commander, General James Mattis said the Governments of Afghanistan and Pakistan would be invited to participate into the investigation.

The investigation team has also been directed to include input and participation from NATO-led International Assistance Security Force (ISAF) of Pakistan.

"It is USCENTCOM's intent to include these government representatives to the maximum extent possible to determine what happened and preclude it from happening again," an official release said.

Brig Gen Clark, from Headquarters Air Force Special Operations Command at Hurlburt Field in Florida, has been directed to provide an initial report by December 23, the release said.

"The investigation team will focus their efforts on the facts of the incident and any matters that facilitate a better understanding of the circumstances surrounding the deaths and injuries of the Pakistan forces," it said.

Earlier in the day, the Pentagon Press Secretary, George Little, said the Department of Defense has been working very hard for some time to address areas of disagreement with the Pakistanis.

"We understand there are deep concerns over the incident this weekend and we'll continue to try to engage closely with our Pakistani counterparts," Little told reporters during an off camera news briefing earlier in the day.