The US State Department has said that a nuclear test by North Korea would pose an 'unacceptable threat' to peace and stability in the world and would further isolate Pyongyang.
Earlier, North Korea announced it would conduct its first-ever nuclear test at some point in the near future and blamed what it said was a US 'threat of nuclear war and sanctions' for forcing its hand.
In a statement, the North Korean foreign ministry claimed that financial restrictions imposed by the Bush administration showed it was trying to stifle North Korea's economy and bring down its communist system.
It also accused the US of, in effect, declaring war by pushing for the UN resolution in July that imposed sanctions on North Korea over its test firing of missiles.
While no date or time was given for the planned test, the announcement was condemned by neighbour Japan as 'totally unforgivable'.
Six nation talks, aimed at ending the nuclear programme, broke down last year when North Korea walked out. It has refused to return until the US ends a financial crackdown on its offshore bank accounts.
A nuclear test will be seen as an attempt by North Korea to force the US into direct negotiations, something it has long pushed for but which Washington has rejected.
