The UN Security Council is to meet Sunday over mounting tensions on the Korean peninsula as US troubleshooter Bill Richardson urged the North to show 'maximum restraint' over a live-fire drill planned by Seoul. Pyongyang has threatened 'disaster' if the South stages the drill on Yeonpyeong Island near the disputed Yellow Sea border, where four people were killed in an artillery bombardment by the North in November. The flare-up, coming in the wake of nuclear-armed North Korea revealing a uranium enrichment programme, sparked alarm around the world. But the UN Security Council has yet to pass any resolution over the incident, which left two marines and two civilians dead and damaged dozens of homes. China, the North's sole major ally, has blocked demands for a strongly worded statement against Pyongyang and talks over a text are now in deadlock. After Seoul announced that the exercise would go ahead Russia called for the Security Council to meet in 'emergency' session on Saturday and Moscow expressed anger that Sunday's meeting was not organised earlier. 'We regret that. We believe that such a step by the president is a departure from the practice existing in the council,' Russia's UN envoy Vitaly Churkin said. The United States, which is president of the Security Council for December, rejected criticism of the arrangements for the meeting. 'This meets other Security Council members' requests to have time to consult with their capitals and meets the Russian request for a timely meeting,' said US mission spokesman Mark Kornblau. Seoul Sunday rejected calls for the drill to be abandoned. The foreign ministers of China and Russia held telephone talks Saturday and urged South Korea to cancel the exercise. 'China firmly opposes any actions to cause tension and worsen the situation, and demands both sides on the peninsula show calmness and restraint,' Chinese Foreign Minister Yang Jiechi said. The Koreas must 'carry out dialogue and contact, and completely avoid any actions that would fuel the tension,' Yang said. But the South said the one-day drill on Yeonpyeong, near the disputed Yellow Sea border, may take place on Monday or Tuesday. On Sunday, a South Korean military aircraft was flying over Yeonpyeong, with marines on patrol near their seaside barracks. Richardson urged North Korea to show 'maximum restraint' at three important meetings with top military and foreign ministry officials in Pyongyang, his office said Sunday. 'During each meeting, I have strongly urged maximum restraint in response to South Korea's planned military drills,' the New Mexico governor and close ally of US President Barack Obama said in a statement. Richardson, whose visit to North Korea is officially in a private capacity, said that he hoped the UN Security Council meeting would result in a strong resolution urging all sides to show self-control. 'A UN resolution could provide cover for all sides that prevents aggressive military action,' he said. On Saturday he described the situation as a 'tinderbox' but said he had made 'a little headway' in talks with North Korean officials. The first shelling of civilian areas since the 1950-53 war sparked outrage in the South, which rushed more troops and guns to frontline islands. The North has threatened 'disaster' if the South stages a live-fire drill on Yeonpyeong. A foreign ministry statement Saturday accused US troops -- some 20 of whom who will take part in the drill -- of providing a 'human shield' for the event. The North said the exercise 'would make it impossible to prevent the situation on the Korean peninsula from exploding and escape its ensuing disaster'. US State Department spokesman Philip Crowley on Friday defended the South's right to hold the drill in the face of North Korea's 'ongoing provocations'. He said Washington trusts that the South 'will be very cautious in terms of what it does'. 