Afghan President Hamid Karzai summoned the NATO commander and the US ambassador on Monday to warn that civilian casualties in military operations threatened a strategic pact he has signed with the US.

Tens of civilians -- including women and children -- had been killed in NATO bombardments in four provinces since Saturday, a statement from Karzai's office charged.

The president warned that if Afghan lives were not protected the Strategic Partnership Agreement he signed with US President Barack Obama last week would "lose its meaning", the statement said.

"The Afghan president this evening summoned NATO Commander General John Allen and US Ambassador Ryan Crocker for an emergency meeting at the Presidential Palace," the president's office said.

He "expressed his concerns about the civilian casualties incurred by our people in four provinces" -- Logar and Helmand in the south, Kapisa in the east and Badghis in the northwest.

The president said civilian casualties always hurt Afghan-American relations, adding that Afghanistan had signed the strategic pact with the US to prevent such incidents and safeguard the lives of Afghans.

"If the lives of Afghans are not protected, the strategic partnership will lose its meaning," the statement quoted the president as saying.

The pact covers relations between the two countries when US-led NATO forces helping Karzai's government fight a Taliban insurgency pull out in 2014.

Allen said after the meeting that he assumed personal responsibility for incidents in which civilians were killed and expressed condolences to the families involved, a spokesman for NATO's International Security Assistance Force (ISAF) told AFP.

"He said he will fully investigate these incidents and report back to President Karzai," the spokesman said. "We don't have all the facts right now."

A NATO airstrike targeting militants in Badghis province on Saturday night killed fifteen civilians, including women and children in Joikar village, Bala Murghab district, provincial member of parliament Qazi Abdul Rahim told AFP.

An ISAF spokesman said earlier, ahead of the meeting with Karzai, that an airstrike killed three insurgents in an attack in the area, but reports indicated no civilians were involved.

In a separate incident, in the volatile Helmand province in southern Afghanistan on Friday, six civilians were killed in a NATO airstrike, an Afghan official said.

"Six people -- a woman, two boys and three girls -- were killed in a foreign forces airstrike on Friday in Sangin district," provincial spokesman Daud Ahmadi told AFP.

ISAF said they were aware of the allegation and "an investigation is under way".

Civilian casualties have always been a sensitive issue in the US-led war against a Taliban insurgency and have often been the cause of tense relations between Kabul and Washington.

The number of civilians killed has risen steadily each year for the past five years, reaching a record of 3,021 in 2011, the great majority caused by militants, according to UN statistics.