The United States says it won't halt air strikes in Afghanistan, as demanded by President Hamid Karzai, and denied using burning phosphorus in the attacks.

U.S. Army General David Petraeus, head of U.S. Central Command, addresses an audience during a forum at the John F. Kennedy School of Government on the campus of Harvard University, in Cambridge, Mass., Tuesday, April 21, 2009. [Steven /SenneAP Photo]

White House National Security Advisor James Jones said on U.S. television the United States would redouble efforts to make sure innocent civilians are not killed, but it won't stop the airstrikes.

Army General David Petraeus, who oversees military operations in Afghanistan, also said on U.S. television that he had named a U.S. brigadier general to look at the use of air strikes.

Petraeus said it was important to ensure the tactical actions don't undermine strategic goals and objectives.

The U.S. military acknowledged on Saturday last week's air strikes in western Afghanistan had struck crowded homes in two villages in Farah province and killed civilians. Afghan president Hamid Karzai has ordered a thorough investigation.

(CCTV May 11, 2009)