Syria’s government and its ally Russia accused Washington on Thursday of concocting a “provocation” in Syria, which would then be blamed on President Bashar Assad’s government as alleged use of chemical weapons to justify an attack.

In a statement carried by the official news agency, Syria’s Foreign Ministry said it rejects U.S. allegations that Syria was preparing for a chemical weapons attack, describing such accusations as “misleading” and “completely baseless.”

It said the objective of such allegations was to “justify a new aggression on Syria under ill-founded pretexts,” similar to what happened in April when the U.S. struck a Syrian air base, which it said had been used to stage a chemical attack on the town of Khan Sheikhoun that killed nearly 90.

Earlier this week, the White House has warned that Assad is preparing for another chemical attack and said that the Syrian ruler will “pay a heavy price” if he unleashes it.

Also Thursday, Russian Foreign Ministry spokeswoman Maria Zakharova said Moscow has received information that Syrian rebels have already fabricated video materials to accuse Damascus of a chemical attack.

She said that according to the information Russia has, Syrian towns of Saraqib and Arihah could serve as venues for the “provocation.” Both towns are located in the province of Idlib in northwestern Syria and are controlled by the rebels.

She claimed that such action could be aimed at derailing the next round of Syria peace talks brokered by Russia, Turkey and Iran, which is set for next week in Kazakhstan’s capital, Astana. The meeting is meant to determine specifics related to safety zones in Syria.

Zakharova’s strongly-worded statement reflect soaring tensions between Moscow and Washington even as U.S. President Donald Trump and Russia’s Vladimir Putin are expected to hold their first meeting at the sidelines of the G-20 summit in Germany.

The U.S. in April struck the Shayrat air base in central Syria, which it said had been used to stage a chemical attack on the town of Khan Sheikhoun. The Pentagon said the preparations detected by the U.S. occurred at the same Shayrat air base which the U.S. named as the platform for launching the April attack.

The Syrian government has denied it ever used banned chemicals, and it rejected Washington’s latest allegations.

Russia also has strongly denied that Assad’s forces were to blame for the attack in April, arguing that the victims had died of exposure to toxic agents released when Syrian warplanes hit a rebels’ chemical weapons depot.

Moscow claimed that some of the images from the scene were fabricated and criticized the international chemical weapons watchdog of failing to send its inspectors to the site of the attack and the Syrian air base allegedly used to launch it.

Russia’s Foreign Minister Sergey Lavrov confirmed on Thusrday that U.S. Secretary of State Rex Tillerson in a phone call this week told him that Washington has information about Assad allegedly preparing a chemical attack.

Lavrov questioned the veracity of the U.S. information and suggested that extremists could take advantage of the U.S. warning to stage a provocation in order to blame Assad.

Asked how Russia would react to a possible U.S. strike on Syria, Lavrov said that the response will be “proportionate.”

(AP)