WASHINGTON (Reuters) - A U.S. military investigator said on Wednesday that a March 16 air strike near Aleppo, Syria, was a valid and legal attack on a meeting of al Qaeda fighters and did not kill dozens of civilians as reported, a finding disputed by Human Rights Watch.

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An investigation of the attack on a building in Al-Jina village identified only one person who might have been a civilian who was wounded or possibly killed, Army Brigadier General Paul Bontrager, deputy director for operations for U.S. Central Command, told a Pentagon briefing by telephone.

He said the strike, in which aircraft dropped 10 bombs on the building and fired two missiles at targets fleeing the site, was believed to have killed about two dozen men attending an al Qaeda meeting at a madrassa, or religious school, under construction.

“We considered media reports that indicated a large number of civilians were killed, but our investigation did not uncover evidence to support those claims,” said Bontrager, adding that investigators were unable to visit the scene or talk to anybody who was on the ground at the time.

The Syrian Observatory for Human Rights, a British-based war monitor, had said at least 49 people were killed and dozens wounded in an attack that hit a mosque with worshippers.

Bontrager said investigators did not speak to the Observatory but did consider a similar Human Rights Watch report.

That assessment said the strike hit the Omar Ibn al-Khatab mosque where about 300 people had gathered for evening prayers. It said at least 38 people were killed in the strike.

Responding to the Pentagon’s investigation on Wednesday, Human Rights Watch issued a statement saying it had found no evidence to support the military’s claim the building was being used by al Qaeda militants.

HRW Washington Director Sarah Margon said in a statement the group spoke to people who were present at the mosque who denied any al Qaeda members were there.

She noted that Syria Civil Defense recovered 38 bodies and relatives identified 28, including the mosque’s imam and his wife. She said HRW independently confirmed 10 of those names in interviews with local residents and medical personnel.

Bontrager said his investigation concluded the strike hit a religious school under construction. He said a mosque across the street was not damaged. A building connected to the madrassa by a stairwell and breezeway was a mosque under construction, he said.