Image copyright Getty Images Image caption US Secretary of State Mike Pompeo has ordered an investigation into the Syrian strike
The US military has launched an investigation into allegations that Syrian forces killed dozens of civilians in an air strike on rebel-held territory in Syria.
US Secretary of State Mike Pompeo said he was “deeply disturbed” by reports that civilians may have been killed.
The strike targeted a logistics warehouse for al-Qaeda fighters near the town of Bir al-Ghanam in eastern Syria.
The warehouse was reportedly damaged.
But at least 35 people have been reported killed in the attack.
The New York Times has reported that at least 15 men died in an attack that appears to have targeted the building where they were gathered in Bir al-Ghanam.
Other reports have suggested the dead included women and children.
Both President Donald Trump and President Bashar al-Assad have yet to comment on the incident.
‘Mean and unwarranted’
The White House has released a statement condemning “the escalation of violence in Syria and its undeniable targeting of civilians”, saying its own investigation was being conducted to ascertain whether civilians had been harmed in the attack.
In a statement, General Joseph Dunford, chairman of the Joint Chiefs of Staff, said “initial indications are that a Syrian regime regime air strike destroyed a storage facility of the al-Qaeda-affiliated Levant Liberation Committee in eastern Syria today”.
General Dunford said investigations into previous alleged Syrian chemical attacks were completed in eight days, while this one would take longer.
While there was no report that al-Qaeda had been in the building, Donald Trump had on Saturday warned the president of al-Qaeda in Syria.
On Saturday, after US-led air strikes hit what US officials called military facilities in Syria belonging to al-Qaeda, Mr Trump said he had used the strike to send a “strong message” to the group.
Last week, in the aftermath of what Syrian opposition forces called “military victories” by government forces, there were reports of a number of civilian casualties, including shootings, in eastern Syria.
Al-Jazeera quoted an unnamed representative of the Jund al-Aqsa brigade as saying a “huge number” of civilians were killed in Saturday’s attack on Bir al-Ghanam, about 70km (45 miles) east of Deir al-Zor.
“We have so far heard of 35 killed in their homes, and more injured. About 30 of the dead are children and four of them women,” the representative said.
BBC correspondent Dan Collyns says fighters in the area had been organising supplies and were planning a joint operation with al-Qaeda for the coming days.
A US defence official told the BBC the US believed the suspected warehouse belonged to al-Qaeda and had been hit because it housed anti-tank missiles.
In a statement issued on Saturday, the International Committee of the Red Cross (ICRC) said it had expressed “profound concern” to the US Department of Defence about the possible civilian casualties, “in accordance with UN Security Council Resolution 2208, which requires both sides to respect the protection of civilians”.
Last month, the ICRC wrote to Mr Trump urging him to draw “direct consequences” against Russia and Syria after they were blamed for the chemical attack in Idlib province that prompted the US-led airstrikes.