The United States has called an urgent meeting of the U.N. Security Council for Monday in response to what it says are efforts by some countries "to undermine and obstruct" sanctions against North Korea.

The U.S. Mission announced Friday evening that the meeting will "discuss the implementation and enforcement of U.N. sanctions on North Korea."

The mission didn't name any countries, but U.S. Ambassador Nikki Haley accused Russia on Thursday of pressuring an independent panel of U.N. experts to alter a report on North Korea sanctions that included alleged violations "implicating Russian actors."

Haley said the panel should release the original report, which cited "a massive increase in illicit ship-to-ship transfers of petroleum products" for North Korea in violation of U.N. sanctions. It said some products allegedly were off-loaded from Russian ships, which were identified in the report.

A summary of the experts report obtained in early August by The Associated Press also said North Korea has not stopped its nuclear and missile programs. And it said North Korea is violating sanctions by transferring coal at sea and flouting an arms embargo and financial sanctions.

The Security Council initially imposed sanctions on North Korea after its first nuclear test in 2006 and has made them tougher and tougher in response to further nuclear tests and an increasingly sophisticated ballistic missile program.

Haley said earlier this year that successively tough Security Council sanctions resolutions adopted unanimously had cut off all North Korean exports, 90 percent of its trade, and disbanded its pool of workers send abroad to earn hard currency.

Many diplomats and analysts credit the sanctions with helping promote the thaw in relations between North Korea and South Korea as well as the June meeting between President Donald Trump and North Korean leader Kim Jong Un at which they agreed to the denuclearization of the Korean Peninsula.

But in July, U.S. Secretary of State Mike Pompeo accused North Korea of "illegally smuggling" in refined petroleum products beyond the annual quota of 500,000 barrels allowed under U.N. sanctions.

U.S. documents sent to the Security Council committee monitoring sanctions against North Korea and obtained by AP cited 89 instances between Jan. 1 and May 30 in which North Korean tankers likely delivered refined products "illicitly procured" via transfers from other ships at sea.

The U.S. said Russia and China both informed the sanctions committee that they were supplying refined products to North Korea. China, which is North Korea's closest ally, is responsible for more than 90 percent of the isolated country's trade.

Pompeo said North Korea is also evading sanctions by smuggling coal by sea and across borders, by using cyber thefts and other criminal activities, and by keeping workers in some countries that he didn't name.

All these activities are "generating significant revenues for the regime and they must be stopped," he said.

At the time, Haley criticized "some friends who want to go around the rules," and especially Russia and China for blocking the sanctions committee from demanding that all countries halt shipments of petroleum products to North Korea immediately.

After the experts' report was released in August, Russian Ambassador Vassily Nebenzia said he put a hold on its official release to all U.N. member nations "because we disagree with certain elements" that he refused to disclose.

Russia and China then blocked the U.N. from imposing sanctions on Russia-based entities and vessels sanctioned a week earlier by the U.S. Treasury Department.

The Russian news agency TASS quoted Russia's U.N. Mission as saying the proposed sanctions were "unjustified."

The Security Council has remained united in imposing tougher and tougher sanctions on North Korea, though the differences over the experts' report mark a serious dent in that unity.

U.N. diplomats familiar with discussions said Russia was angered that the panel used a lot of U.S. intelligence in the initial report that Moscow claimed was incorrect. The diplomats spoke on condition of anonymity because talks were private.

Haley expressed disappointment in the panel "for caving to Russian pressure and making changes to what should have been an independent report." She called it "a stain" on the experts' important work.