Russia’s foreign ministry pushed back Saturday against reports that its oil tankers violate UN sanctions by sneakily supplying fuel to North Korea by means of at-sea cargo transfers.

“Russia observes fully the sanctions regime” against Pyongyang, its foreign ministry said.

At least three Russian oil tankers delivered fuel to North Korean vessels in October and November via clandestine ship-to-ship transfers, Reuters reported Friday, citing senior European security sources.

“There is no evidence that this is backed by the Russian state,” one source told Reuters. “But these Russian vessels are giving a lifeline to the North Koreans.”

North Korea imports fuel to power its missile and nuclear programs and maintain its sputtering economy.

The United Nations has sharply restricted North Korea’s oil imports in recent months as part of sanctions aimed it forcing it to back off nuclear weapons tests, missile launches and other belligerent acts.

President Trump on Friday used Twitter to scold China for being “caught RED HANDED” allowing fuel to flow to North Korea. China denied any illicit sales.