The threat was issued by an unidentified "analyst," quoted in the Korean Central News Agency.

"The army and people of the DPRK are now in full preparedness to answer a pre-emptive attack with a relentless annihilating strike and a nuclear war with a mighty nuclear deterrent," the report said.

The DPRK stands for the Democratic People's Republic of Korea.

In Monday's report, Washington was accused of putting new spy planes on the Korean peninsula and a massive arms buildup. The U.S. was also slammed for staging war games in the region recently.

"This is a grave military provocation and blackmail to the DPRK, being an indication that the U.S. is rapidly pushing ahead in various fields with the extremely dangerous war moves," the dispatch said.

The report comes amid U.S. claims that Pyongyang has shown signs of preparing for a test of a long-range missile.

Intelligence reports say fuel tanks have been seen around a missile at the North's launch site on its northeastern coast. However, it's unclear if the rocket was actually being fuelled.

Regardless, North Korea claims it has a right to test-fire a long-range missile.

The North has also said it is willing to talk to Washington about its missile concerns in direct meetings with the Americans. However, Washington, insists it will only meet the North amid six-nation talks aimed at ridding Pyongyang of its nuclear weapons program.

With files from The Associated Press