The South's defence ministry said on Sunday it had no plans to respond immediately to the North's message.

On Wednesday, South Korea's new chairman of the Joint Chiefs of Staff, General Kim Tae Young, told parliament the South would strike the North's nuclear sites should the communist country attack it with nuclear weapons.

The North's retort late on Saturday followed its test-firing of several short range missiles on Friday, an action backed by a warning that it could slow down work to disable atomic plants.

'These outbursts are the gravest challenge ever in the history of the inter-Korean relations and a reckless provocation little short of a war declaration against us,' the North's military said in a notice sent to the South's chief delegate to inter-Korean general-level military talks.

'If the south side does not retract the outbursts calling for 'pre-emptive attack' nor clarify its stand to apologise for them, the KPA (Korean People's Army) will interpret this as the stand off the south side' authorities to suspend all inter-Korean dialogues and contacts,' it said.

The warning was the latest among a series of actions and statements from the North over the past week as Pyongyang continues to stonewall a six-nation deal to disable its nuclear weapons programme.

The raft of actions was aimed at the South and the United States as the North is angry at Seoul's tougher policy and continuing US sanctions against the communist state.

'We will counter any slightest move of the South side for 'pre-emptive attack' with more rapid and more powerful pre-emptive attack of its own,' the North's military was quoted as saying late Saturday by the official Korean Central News Agency.

Answering a question about what South Korea should do if the North develops small nuclear weapons and attack the South with them, General Kim said the South should find nuclear sites and strike them with precision weapons.

When the remarks raised tensions last week the Joint Chief of Staff issued a statement of clarification, saying the general was only touching on a possible military operation that could be thought of in such a hypothetical situation.

On Friday, the North's Navy Command issued a fresh warning against the South's warships intruding into its 'territorial waters' in the Yellow Sea, which are claimed by both Koreas.

Bloody clashes involving warships of the two rivals in 1999 and 2002 left tens of casualties on both sides.

The test-firings in the Yellow Sea on Friday were the first in nine months and came after the north expelled South Korean officials from Kaesong industrial park, the most important inter-Korean project and the most visible symbol of reconciliation.

The South's former President Roh Moo Hyun and North leader Kim Jong Il agreed in October 2007 that the two sides hold fresh reunions of separated families in the first half of this year and send a joint supporters group to the Beijing Olympic.

But because of Saturday's statement, these agreements are unlikely to be implemented, news reports here said. -- AFP