WASHINGTON (Reuters) - Russia has been quietly shipping refined petroleum to North Korea at levels that appear to violate a cap imposed by the United Nations Security Council, the White House said on Thursday, suggesting new sanctions could result.

The disclosure came on the first day after a U.N. panel of experts monitoring enforcement of longstanding U.N. sanctions against North Korea for its nuclear weapons and missile programs was disbanded after a Russian veto.

"At the same time that Moscow vetoed the panel's mandate renewal, Russia has been shipping refined petroleum from Port Vostochny to the DPRK (North Korea)," White House national security spokesperson John Kirby told reporters.

Under U.N. sanctions, Pyongyang is limited to importing 500,000 barrels of refined products a year. The Russian and North Korean U.N. missions in New York did not immediately respond to a request for comment on the U.S. accusation.

Kirby said that in March alone, Russia shipped more than 165,000 barrels of refined petroleum to North Korea and that given the close proximity of Russian and North Korean commercial ports, Russia could sustain these shipments indefinitely.

Russia blocked the annual renewal of the U.N. sanctions monitors in late March in what a U.S. official described as a calculated move by Moscow to hides its own violations of UN Security Council resolutions.

Kirby said the United States will continue to impose sanctions "against those working to facilitate arms and refined petroleum transfers between Russia and the DPRK." North Korea is formally known as the Democratic People's Republic of Korea.

"We have previously worked to coordinate autonomous sanctions designations with our partners - including Australia, the European Union, Japan, New Zealand, the Republic of Korea, and the United Kingdom - and we will continue to do so," he said.

The U.S. and South Korea in March launched a task force aimed at preventing North Korea from procuring illicit oil.

The U.S. and others have also accused North Korea of transferring weapons to Russia for use against Ukraine, which it invaded in February 2022. Both Moscow and Pyongyang deny the accusations, but vowed last year to deepen military relations.

The debris from a missile that landed in the Ukrainian city of Kharkiv on Jan. 2 was from a North Korean Hwasong-11 series ballistic missile, U.N. sanctions monitors told a Security Council committee in a report seen by Reuters on Monday.