The Security Council had been due to meet at 1400GMT to vote on the resolution to punish Pyongyang for its nuclear test on Monday. That has been rescheduled until later in the day after John Bolton, the US Ambassador, said that Russia raised "technical problems" on banned weapons.

"We will work tonight on the technical question of what's covered by and how we define nuclear, biological and chemical weapon-related materials and ballistic missiles," Bolton said after a meeting of the permanent five council members - the United States, Britain, France, Russia and China - and Japan.

Wang Guangya, the Chinese ambassador to the UN, told reporters after the meeting that Beijing still had "difficulties" about a provision authorising nations to search cargo going to and from North Korea for nuclear materials or ballistic missiles.

China wants that provision softened so that no interdiction would be mandatory.