AP

KABUL, Afghanistan (AP) — The U.S. failed to properly investigate civilian killings, including possible war crimes, which occurred during its military operations in Afghanistan, the international rights group Amnesty International said Monday. NATO said it would review the report.

A toughly-worded report by the group focused on 10 incidents between 2009 and 2013 that it said saw 140 civilians killed during U.S. military operations. Amnesty said the vast majority of family members it interviewed said they had never been interviewed by U.S. military investigators.

Most of the incidents involved airstrikes and night raids carried out by U.S. forces. Both tactics have sparked heated criticism from Afghan civilians and the government who say the U.S. doesn't take enough care to prevent civilian deaths.

Two of the cases — one in Paktia province in 2010 and another in Wardak province from November 2012 to February 2013 — involved "abundant and compelling evidence of war crimes," the report said.

"None of the cases that we looked into — involving more than 140 civilian deaths — were prosecuted by the U.S. military," Richard Bennett, Amnesty International's Asia Pacific Director, said in a statement. "Evidence of possible war crimes and unlawful killings has seemingly been ignored."

A spokesman for NATO forces in Afghanistan, Lt. Col. Chris Belcher, said authorities were reviewing the report and would respond later. He stressed that they take allegations of civilian casualties seriously and thoroughly investigate all such reports.

Afghan civilians increasingly find themselves under fire as the 2001 U.S.-led war draws to a close, as Afghan forces take the lead in operations targeting the Taliban. The civilian death toll in the war in Afghanistan rose 17% for the first half of this year, the United Nations reported in July. The U.N. said 1,564 civilians were killed from January through June, compared with 1,342 in the first six months of 2013.

However, the U.N. found that Taliban fighters and other militants have been responsible for the majority of the civilian killings. Insurgents were responsible for 74% of the casualties, the U.N. said, while pro-government forces were responsible for 9 percent, government forces 8% and foreign troops just 1%. The rest could not be attributed to any group.

In its report, Amnesty International said U.S. and NATO forces have made significant strides toward preventing civilian casualties, though lingering questions over the 10 incidents it cited casts a pall over their efforts.

"The legacy of international military operations is seriously tainted, however, when military forces leave behind families whose efforts to seek justice have been ignored," the report said.