U.S. and Pakistani investigators have reached "separate" conclusions about why warplanes killed 11 Pakistani troops at an outpost near the Afghan border, the Pakistan army said Thursday.

The June incident has put a heavy strain on crossborder military relations just as NATO commanders in Afghanistan call for greater cooperation to combat resurgent Taliban militants.

U.S. officials have said aircraft dropped more than a dozen bombs during a clash with militants near the border post in Pakistan's Mohmand region. Though they expressed regret over the incident, they have said the action was justified.

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But Pakistan army spokesman Maj. Gen. Athar Abbas said a joint investigation set up to try to ease tensions had failed to produce an agreement on what happened.

"We have our separate findings. The findings are different," Abbas told The Associated Press.

He declined to give details of the findings because they remain confidential.

However, he said the bombing could not be justified as self-defense.

"In our investigation, there was no act of offense from this side," Abbas said.

The paramilitary Frontier Corps troops manning the border post "never fired a shot on the other side and it was taken by complete surprise when a number of strikes came on their post," he said.

Abbas also disputed a newspaper report that U.S. military planners did not have the coordinates of the base.

Abbas said the coordinates of all the posts on the Pakistani side of the border had been shared with the U.S.-led coalition force in Afghanistan at least three times since 2003.

"Even marked maps were handed over to coalition forces at one stage, indicating the location of our posts," he said.

The New York Times, quoting unidentified American officials, reported on Wednesday that the exact location of the base was not in a database used to prevent so-called friendly fire incidents.

Capt. Christian Patterson, a spokesman for the U.S.-led coalition forces in Afghanistan, said Thursday the incident was still under investigation.

Abbas said the incident had heightened awareness on both sides to improve coordination and communications between troops on either side of the mountainous frontier.

He said the two sides had "generally agreed" on recommendations to address those problems and avert any repeat. Details would be released jointly at a later date, he said.

NATO and the U.S. military contend that Pakistan is not putting enough pressure on militants, giving Taliban and Al Qaeda fighters more leeway to launch attacks on their forces across the border in Afghanistan.