The U.S. National Security Advisor says Washington will not stop air strikes in Afghanistan despite Afghan complaints about civilian casualties caused by the raids.

James Jones told U.S. television Sunday U.S. forces fighting Taliban militants in Afghanistan cannot operate "with one hand tied behind our back," as he put it.

Afghan President Hamid Karzai has demanded an end to the U.S. air strikes, which he says killed up to 130 civilians in the western province of Farah in the past week.

The U.S. military says a joint investigation with Afghan authorities shows Taliban militants used civilians as human shields in the fighting.

The military says the number of civilians killed in Farah cannot be determined because all the bodies were buried before the investigators arrived. Jones, a retired general, says the U.S. will "redouble" its efforts to limit civilian casualties.

The chief of U.S. forces in Central Asia and the Middle East said Sunday on U.S. television the military will "look" at the use of air strikes in Afghanistan. General David Petraeus says U.S. forces must ensure their tactics do not undermine strategic U.S. goals.

Afghan officials complain that civilian casualties caused by U.S. forces undermine the public's faith in the Afghan-U.S. alliance against the Taliban.

In another interview, Petraeus said al-Qaida no longer has bases in Afghanistan after suffering what he called "very serious" losses in the last six to 10 months.

But, Petraeus says affiliates of the group still have "enclaves and sanctuaries" in parts of eastern Afghanistan, near the Pakistani border. He says militant leaders in the region primarily operate out of western Pakistan's lawless tribal regions.

U.S. President Barack Obama, Mr. Karzai and Pakistani President Asif Ali Zardari met in Washington last Wednesday to try to agree on a strategy for combatting militants in the region.

Mr. Karzai said in a U.S. television interview that he has more confidence in Mr. Zardari than in the previous Pakistani president, Pervez Musharraf.

Some information for this report was provided by AFP, AP and Reuters.