North Korea is preparing to test-launch its longest range ballistic missile, according to reports.

The news comes just days after Pyongyang warned that the Korean peninsula was on the brink of war. The hermit kingdom typically launches missiles in periods of political tension.

Last week, North Korea said it was scrapping all agreements with South Korea in a move analysts said was aimed at pressuring Seoul and grabbing the attention of new US President Barack Obama.

Unnamed government sources in South Korea said the North had been moving equipment used in the launch of its Taepodong-2 missile, which Pyongyang last test-fired in July 2006.

A train carrying a large object has been moved from a factory and has headed to the site of a newly constructed missile launch site on the North's west coast, the source said.

"The object is suspected as being a Taepodong-2," he said.

It will take North Korea at least a month or two to actually launch a Taepodong-2, an unnamed Japanese government source said.

A South Korean Defence Ministry official said he could not comment on intelligence matters but added the South keeps a constant eye on the North's military activities.

The last time North Korea fired a Taepodong-2, it misfired shortly after leaving the launch pad. It is designed to eventually have a range long enough to hit US territory.

Much of the preparation needed to get it ready can be seen by spy satellites and aerial reconnaissance.

North Korea has more than 800 ballistic missiles with ranges that can hit all of South Korea and most of Japan.

The North's bureaucracy works slowly to form policy and it may still be trying to figure out its approach with the new Obama team, analysts said, making it easier for Pyongyang to direct its anger at Washington's allies, including Seoul.

The North in recent months has repeatedly threatened to destroy the conservative government of South Korean President Lee Myung-bak, which ended a decade of free-flowing aid to Pyongyang after taking office a year ago.

Mr Lee's government has mostly ignored Pyongyang's taunts.

© Independent Television News Limited 2009. All rights reserved.