BAGHDAD, June 18 (Xinhua) -- The Iraqi Hashd Shaabi paramilitary forces said on Monday that 22 of its members were killed and 12 others wounded in suspected U.S.-led airstrikes on its base inside Syria near the Iraqi border.

The U.S.-led coalition aircraft fired two guided missiles at 10 p.m. local time Sunday night (2000 GMT) targeting a headquarters of the Hashd Shaabi's 45 and 46 brigades, which are tasked with protecting the Iraqi border with Syria from infiltration of Islamic State (IS) militants, the paramilitary forces said in a statement.

The headquarters inside Syria has been known to both the Syrian government and the Iraqi Joint Operations Command (JOC) since the end of operations that liberated the border areas with Syria late in 2017, according to the statement.

The headquarters lies at a strategic spot in the open desert land just 700 meters inside Syria north of its eastern city of al-Bukamal.

"We demand that the American side issue an explanation for the airstrike, especially that such strikes have been repeated throughout the years of confrontation with terrorism," the statement said.

However, a U.S. military spokesman denied that the U.S.-led coalition aircraft conducted any strike in the area, saying "we're looking into who that could possibly be but it wasn't the U.S. or the coalition."

On Dec. 9, 2017, Iraqi Prime Minister Haider al-Abadi officially declared full liberation of Iraq from IS militants after Iraqi forces recaptured all the areas once seized by the extremist group.