Obama's condolences for deadly airstrike

WASHINGTON -- President Barack Obama called Pakistan's president Sunday to offer condolences over a NATO airstrike that killed 24 Pakistani troops and provoked a crisis in relations between the two countries.

Obama told President Asif Ali Zardari that the soldiers' deaths were "regrettable" and accidental, according to a White House statement.

The comments stopped short of a formal apology but were aimed at soothing Pakistani fury over the Nov. 26 incident.

"Earlier today the president placed a phone call to Pakistani President Asif Ali Zardari to personally express his condolences on the tragic loss of twenty-four Pakistani soldiers this past week along the border of Afghanistan and Pakistan," the White House statement said. "The president made clear that this regrettable incident was not a deliberate attack on Pakistan and reiterated the United States' strong commitment to a full investigation."

The NATO airstrike has added to strains in relations with Islamabad, whose cooperation Washington views as crucial to helping to stabilize the region before foreign combat troops leave Afghanistan in 2014.

U.S.-Pakistani relations were already frayed after the secret U.S. raid in May that killed al-Qaida leader Osama bin Laden.

Obama's phone call came on the eve of an international conference in Germany on the future of Afghanistan.

Pakistan is boycotting the conference because of the NATO airstrikes.

On Saturday, Secretary of State Hillary Rodham Clinton spoke by phone with Pakistani Prime Minister Yusuf Raza Gilani to offer condolences.

U.S. and Pakistani officials have offered differing initial accounts of what happened at the Pakistani posts near the border with Afghanistan.

Pakistan said the attack was unprovoked, with officials calling it an act of blatant aggression, an accusation the United States has rejected.

Two U.S. officials have told Reuters that preliminary information from the continuing investigation indicated Pakistani officials at a border coordination center had cleared the airstrike, unaware they had troops in the area.