U.S. Ambassador to the U.N. Nikki Haley is engaged in a “fake diplomacy” campaign, Russian Foreign Minister Sergey Lavrov alleged Friday.

Lavrov attacked Haley following a particularly contentious U.N. Security Council meeting Thursday, which saw the Russian government veto an American-led effort to reauthorize a panel investigating chemical weapons attacks in Syria. Russia has criticized the U.N. investigators who concluded that Syrian President Bashar Assad used chemical weapons against his own people in its civil war.

“It seems, we are witnessing a new phenomenon in international relations, as now, apart from fake news, there is also fake diplomacy,” Lavrov said Friday, per state-run media.

The jibe is modeled on the “fake news” label popularized by President Trump’s rhetorical war with prominent media outlets. Lavrov’s accusation extends a diplomatic dispute over the Joint Investigative Mechanism for investigating gas attacks that descended into allegations of bad faith at the U.N. Security Council on Thursday.

“Russia wants [an investigative] mechanism, but not an independent one,” Haley said. “It puts this Council in the absurd position of putting the fox in charge of the hen house; having countries like Russia and Syria dictate how, when, and where we investigate the use of chemical weapons.”

The Joint Investigative Mechanism is set to expire on Friday. U.N. diplomats have clashed repeatedly over the details of plans to renew the body, as Russian officials have maintained that Assad has been blamed unfairly for the use of chemical weapons.

"On the basis of false information, it will time after time accuse the Syrian government of violating international norms,” Russian U.N. Ambassador Vasily Nebenzya said during the debate.

That’s an apparent reference to Russian protests that the U.N. investigators failed to collect their own soil samples from the site of an April chemical weapons attack that provoked a U.S. counterstrike. But U.S. diplomats have dismissed those concerns, noting that the soil samples were provided by the Assad regime itself.

“If you pay attention, you will notice that the Russians think the JIM works great when it finds ISIS at fault for chemical weapons,” Haley said. “But when it is one of their friends who is the perpetrator, the problem is suddenly the JIM, not their friend who committed the crime.”

Haley added that the U.S. offered to make numerous modifications to a resolution that would renew the Joint Investigative Mechanism, only to be rebuffed by Russia, while the Russian side failed to negotiate on the terms of their alternative resolution. "For some reason, the phones at the Russian Mission [at the U.N.] aren't working," she told reporters. "We have tried to get a call with them, and they've been too busy to talk to us this week.”

Lavrov denied that claim. “We have read all the reports provided by our New York mission — no such efforts were rejected,” he said.