South Korea seized a Hong Kong-flagged vessel suspected of transferring oil to North Korea in defiance of international sanctions on Dec. 24, Reuters reported Friday.

The vessel, Lighthouse Winmore, transferred refined petroleum products to a North Korean ship in international waters in late October, a foreign ministry official told Reuters.

The United States proposed blacklisting the Hong Kong-flagged ship to the U.N. Security Council for circumventing sanctions slapped on North Korea for its nuclear and missile programs, documents seen by Reuters this month showed.

In a tweet, President Donald Trump said China was “caught red-handed.”

China denied Friday that it was supplying oil to North Korea, USA Today reported.

Hua Chunying, a spokeswoman for China’s Foreign Ministry, said Friday that Beijing has “completely and strictly” complied with the sanctions, The Associated Press reported.

She said that authorities investigated a report that a Chinese ship had transferred oil to a North Korean ship at sea in October and concluded the report was false.

The Lighthouse Winmore departed from the port of Yeosu in South Korea, CNN reported.

“UN Security Council sanctions prohibit the transfer of anything to a North Korean ship,” the official told CNN. "This is one of the main ways in which North Korea uses an illegal network to circumvent UN Security Council sanctions.”