UNITED NATIONS (Reuters) - China has told UN Security Council members it plans to block publication of a UN special report that accuses North Korea of violating sanctions on its nuclear program, Western diplomats said. The UN Panel of Experts on North Korea submitted a report on January 27 to the Security Council's sanctions committee, which monitors compliance with UN sanctions on Pyongyang imposed after its two nuclear tests. Diplomats told Reuters that China informed council members it would block the publication and transfer of the report to the full council. They said China's move was odd since one of the experts who prepared the report, Xiaodong Xue, is Chinese. The panel's report, which was seen by Reuters, says that North Korea almost certainly has several more undisclosed enrichment-related facilities. It also says that Pyongyang's uranium enrichment program and its development of a light-water reactor are serious violations of UN sanctions. The report of the panel, which includes experts from the five permanent Security Council members, South Korea and Japan, was partly based on conversations with US nuclear scientist Siegfried Hecker, who saw around 2,000 centrifuges used to enrich uranium during a rare visit to North Korea last year. The North Korean sanctions committee will present on February 23 its quarterly update on compliance with the UN sanctions imposed on Pyongyang after its 2006 and 2009 nuclear tests. Western diplomats said they hoped the sanctions committee could meet before February 23. But China has made it difficult to schedule a committee meeting, they said, and wanted as few details as possible of the panel's enrichment assessment and Hecker's visit to North Korea mentioned in the committee's quarterly update. Sanctions committees work on the basis of consensus, which gives China and all other Security Council members the power to block decisions. Beijing has prevented the transfer to the Security Council and publication of other expert panel reports on North Korea and Sudan in the past. Diplomats say it is emblematic of China's increasingly self-confident approach to international diplomacy as it seeks to protect states like North Korea to which it has close ties. The panel's report raises a number of concerns about North Korea's nuclear program. As Reuters reported last month, it says Pyongyang likely has further secret facilities and calls for better implementation of the sanctions. The panel also voiced concern that North Korea might "transfer fissile materials or the means of producing them" to foreign countries due to its shortage of hard currency. The panel has previously suggested that Pyongyang may have aided Syria, Myanmar and Iran with nuclear or missile technology. The panel concluded that the North's enrichment program, which Pyongyang says it began in April 2009, must have been developed much earlier, over the course of "several years or decades" and appears mainly to be for military purposes. The report says the chief engineer at North Korea's Yongbyon nuclear complex told Hecker of a further facility for processing and converting uranium to a form usable in centrifuges but refused to show it to the American scientist. North Korea's centrifuges, it said, are based on equipment Pyongyang received from Abdul Qadeer Khan. North Korea says its centrifuges were developed domestically. The expert panel, however, says that "more recent illicit attempts of acquisitions" of items from abroad that are crucial for centrifuge production cast doubt on that. Like Iran, the panel said North Korea is using second-generation Pakistani-type equipment - known as "P-2" centrifuges. For some reason, however, the North Koreans have achieved far better results than the Iranians. Among the likely reasons for that, North Korea appears "to have cooperated more closely with AQK (Khan) than Iran, possibly receiving training in the assembly, operation and maintenance of centrifuges," the report says. It added that there was no reason to doubt reports that some 200 North Korean nuclear engineers graduate every year.