The U.N. Security Council will hold an emergency meeting Friday on alleged manufacture of biological weapons in Ukraine at the request of Moscow, whose credibility on chemical weapons was questioned during a session on Syria.

Russia on Thursday accused the United States of funding research into the development of biological weapons in Ukraine, which has faced an assault by tens of thousands of Russian troops since Feb. 24.

Both Washington and Kyiv have denied the allegations, with the United States saying they were a sign that Moscow could soon use the weapons itself.

Ukrainian President Volodymyr Zelenskyy dismissed Russia’s allegations in a video address on Thursday, saying, “No one is developing any chemical or any other weapons of mass destruction” in Ukraine.

Western states have charged that Russia is employing a ruse by accusing their opponents and the United states of developing biological and chemical weapons to lay the ground for their possible use in Ukraine — something Moscow has been accused of doing in Syria.

At a monthly Security Council meeting on the use of chemical weapons in Syria — a case that remains unresolved and continues to suffer from a U.N.-denounced lack of information from Damascus — both Washington and London raised Ukraine.

“The Russian Federation has repeatedly spread disinformation regarding Syria’s repeated use of chemical weapons,” the deputy U.S. envoy to the U.N., Richard Mills, said.

“The recent web of lies that Russia has cast in an attempt to justify the premeditated and unjustified war it has undertaken against Ukraine, should make clear, once and for all, that Russia also cannot be trusted when it talks about chemical weapon use in Syria.”

Mills’ U.K. counterpart, James Kariuki, denounced Moscow’s attack on Ukraine and said the “parallels with Russian action in Syria are clear.”

“Regrettably, the comparison also extends to chemical weapons, as we see the familiar specter of Russian chemical weapons disinformation raising its head in Ukraine.”

In 2018, Moscow accused the United States of secretly conducting biological weapons experiments in a laboratory in Georgia, another former Soviet republic that, like Ukraine, has ambitions to join NATO and the European Union.

The Security Council meeting Friday is slated to begin at 11 a.m. (1600 GMT).