The first U.S. soldier killed in the recent Operation Anaconda sweep against al-Qaida fighters in eastern Afghanistan may have been a so-called friendly fire casualty.

At first it was thought Army Chief Warrant Officer Stanley Harriman was killed by enemy fire in a March 2 attack on a convoy of American and Afghan forces in the Shah-i-Kot area.

Now, however, the commander of U.S. troops in Afghanistan has disclosed the death may have been caused by fire from a U.S. AC-130 gunship flying in the same area which thought it was engaging an enemy convoy.

Army four-star General Tommy Franks tells reporters at the Pentagon the incident is now under investigation. "The coincidence of the timing of the AC-130 strike and the strike on that convoy were in my view sufficient to cause me to ask the question," General Franks said.

The previously undisclosed investigation is revealed in a document released Friday listing 10 incidents involving friendly fire or civilian casualties that have been or are being reviewed by military officials.

They include a January raid on two suspected al-Qaida or Taleban compounds north of Kandahar that led to the deaths of 16 Afghan civilians who were later determined to be neither Taleban nor al-Qaida. The document notes an investigation found there were no errors in the target selection, mission planning or mission execution.

Another incident involves the bombing by U.S. aircraft of Red Cross storage facilities in Kabul. In this case, an official inquiry found the coordinates for these facilities were not included on a list provided to U.S. military authorities by the Red Cross in advance of the American offensive in Afghanistan.

General Franks says U.S. military officials hope to learn from each of the incidents. But he says it is impossible to eradicate the loss of innocent lives in warfare.

The report issued by the U.S. military's Central Command says in six months of operations against terrorists and their supporters in Afghanistan, coalition forces have flown over 36,000 missions and dropped more than 21,000 weapons.