The foreign ministry statement appeared to cast doubt on an early resumption of six-party talks aimed at moving on to the final stage of the agreement.

It came only a week after the communist state dramatically blew up the cooling tower at its plutonium-producing Yongbyon atomic complex in front of foreign TV cameras.

"This showed our commitment to denuclearisation," a ministry spokesman told the official Korean Central News Agency.

The timeframe for the current phase of the deal was set out in an agreement reached last October 3 between the two Koreas, the United States, Japan, China and Russia.

Under the current phase the North should get energy aid equivalent to one million tons of fuel oil and the lifting of some US sanctions, in return for disabling Yongbyon and documenting its nuclear activities.

Last week the North -- which tested a nuclear weapon in October 2006 -- handed over the long-awaited nuclear declaration to China, the host of the six-party talks.

He complained that while 80 per cent of the Yongbyon facility has been disabled, only 40 per cent of the promised energy aid has been delivered.

The spokesman also complained that Washington's decision to drop the North from a terrorism blacklist has not yet taken effect "due to procedural reasons."