US envoy John Bolton said he hoped the new draft, which is due to be tabled later, would pass by the weekend. The draft targets the North?s missile and nuclear programmes and invokes the UN?s Chapter Seven, which could eventually involve the use of force.

But divisions remain among key nations, with China unhappy with the new draft. The underground test reportedly took place at 1036 (0136 GMT) on Monday in Gilju in north-east Hamgyong province. Russia is the only country to have confirmed that it was a nuclear explosion, amid speculation the test was not wholly successful.

North Korea has said it will take ?strong countermeasures? against Japan if it goes ahead with new sanctions against the country, a senior North Korean diplomat was quoted as saying yesterday.

?The specific contents will become clear if you keep watching. We never speak empty words,? Song Il-Ho, the North?s ambassador in charge of normalising relations with Tokyo, told Japan?s Kyodo news agency.

North Korea?s threats are part of a campaign to make the world think twice about its response to the nuclear test, says the BBC?s Charles Scanlon in the South Korean capital, Seoul.

On Wednesday, Japan imposed its own tough new sanctions on North Korea, including banning all imports from the country. The sanctions were expected to be approved by the Japanese cabinet yesterday.

Yesterday, South Korea said it had not detected any abnormal radioactivity levels in its country after the alleged North Korea nuclear test.

There is agreement in the UN Security Council that North Korea should face punitive measures, but countries are divided over how tough these should be.

The US wants the sanctions - which would also target luxury goods ? to be brought under Chapter Seven of the UN Charter. This means they would be mandatory and ultimately enforceable by military means.

But China, Russia and South Korea have expressed varying degrees of opposition to such a resolution. China is also reported to be unhappy about authorising inspections of cargo vessels moving in and out of North Korea in order to find weapons-related material.

Both China and South Korea are worried that such inspections could provoke military action from North Korea ? a risk neither country is willing to take, correspondents add. The new draft retains the call for cargo inspections but is reported to soften language in some key areas of the document.

It also includes a clause allowing nations to ban the entry or transit of people believed to support Pyongyang?s weapons programme, reports say.