Obama expresses regret for deaths

KABUL, Afghanistan - US President Barack Obama expressed "deep regret" to President Hamid Karzai over recent civilian deaths in military operations in Afghanistan during a call, Karzai's office said on Thursday.

On Wednesday, the US commander of international troops in Afghanistan, General David Petraeus, said he was "deeply sorry" after nine civilians died in a coalition air strike in Kunar province, northeast Afghanistan, on Tuesday.

Karzai says those who died were nine young children out collecting firewood and has warned that international troops in Afghanistan face "huge problems" if the "daily killing of innocent civilians" does not stop.