The allegations, made by Russia’s Defense Ministry, center on a US military base at Tanf, a strategic Syrian highway border crossing with Iraq in the south of the country, Reuters wrote.
Russia says the US base is illegal and that it and the area around it have become “a black hole” where terrorists operate unhindered.
The United States says the Tanf facility is a temporary base used to train partner forces to fight against Daesh. Pentagon spokesman Colonel Robert Manning on Tuesday said Washington remained committed to killing off Daesh and denying it safe havens and the ability to carry out strikes.
But Major General Igor Konashenkov, a spokesman for the Russian Defense Ministry, said Moscow wanted to know how around 300 Daesh terrorists in pickup trucks had passed through the US-controlled area and tried to block the highway between Damascus and Deir ez-Zor used to supply Syrian forces.
He said the US had not yet given an explanation.
“We suggest the American side also explain about another incidence of their ‘selective blindness’ towards terrorists operating under their nose,” Konashenkov said in a statement.
He said about 600 terrorists based in a refugee camp in the US controlled area had driven en masse to a former customs post called Tafas on the Syrian-Jordanian border earlier this month and seized food and medical supplies meant for locals.
“You don’t need to be an expert to now forecast an attempt to rupture the peace agreement in the southern de-escalation zone,” said Konashenkov.
“We issue a warning. All responsibility for sabotaging the peace process will lay exclusively with the American side.”
Meanwhile, the Syrian foreign minister accused the US-led coalition of wreaking destruction in Syria while sparing the Daesh terror group, foxnews.com reported.
Walid al-Muallem said during a visit to Russia on Wednesday that the US-led coalition has been "methodically destroying all except Daesh." He said Washington aims to destroy Syria's economy and drag the war out.
Muallem said the Kurds are now vying for control of oilfields in eastern Syria and warned that Syria will reassert its sovereignty over the area.
The US-led coalition has been conducting airstrikes against what are said to be Daesh targets inside Syria since September 2014 without any authorization from the Damascus government or a UN mandate.
The military alliance has repeatedly been accused of targeting and killing civilians. It has also been largely incapable of achieving its declared goal of destroying Daesh.