South Korea called Wednesday for preliminary military talks with North Korea next month, in what would be their first dialogue since the North's deadly shelling of a border island two months ago.

Visiting US Deputy Secretary of State James Steinberg strongly backed the talks, calling them "a critical first step" towards any wider dialogue.

He also expressed concern at a uranium enrichment programme disclosed by the communist state last November, saying it breaches the North's international obligations.

The two Koreas agreed in principle last week to hold high-level military talks to ease months of tensions sparked by the shelling, the nuclear disclosure and the sinking of a South Korean warship last March.

Seoul's defence ministry said it sent a message to the North suggesting a working-level meeting on February 11 at the border village of Panmunjom, to set the date and agenda for higher-level military talks.

The proposal came as Steinberg briefed South Korea on last week's Washington summit, at which US President Barack Obama and his Chinese counterpart Hu Jintao expressed concern at the flare-up on the peninsula.

The North killed four people including civilians when it shelled and rocketed a South Korean island on November 23. Seoul also accuses its neighbour of torpedoing a warship last March with the loss of 46 lives, a charge it denies.

The South said it would demand at the working-level talks that its neighbour takes "responsible measures" over the attacks and pledges not to repeat them.

The North has said only that it wants to discuss its "viewpoint" on the incidents.

The South also urged the North to hold separate nuclear talks with Seoul to confirm its willingness for denuclearisation.

In response the North accused the South of setting "unilateral preconditions" and trying to manipulate the order of talks.

"It is necessary to guard against the assertions intended to unilaterally put up preconditions or deliberately set the order of various dialogues," a foreign ministry spokesman said in a statement published by the country's official Korean Central News Agency.

The spokesman also called for "a modality of dialogue" to eliminate the root cause of a nuclear standoff.

"The nuclear issue on the peninsula surfaced due to the US threat of a nuclear war and its hostile policy towards (North Korea) and it is, therefore, essential to find a modality of dialogue for eliminating its root cause," he said.

China is trying to revive a stalled six-nation nuclear disarmament forum. But South Korea says the issue should also be discussed bilaterally, something the North has baulked at.

Pyongyang says its uranium enrichment plant is part of a peaceful energy programme, but experts say it could easily be reconfigured to produce weapons-grade uranium, giving North Korea a second way to make nuclear bombs.

China, the North's sole major ally, for the first time publicly expressed concern at the uranium programme in a summit joint statement last week.

Steinberg said the international community must "send a strong message" that the programme breaches UN Security Council resolutions and the North's own previous disarmament commitments.

"I think the strong position we've all taken and I think the clear message coming out of the summit between President Obama and President Hu should help drive the message home," he said after talks with Foreign Minister Kim Sung-Hwan.

Steinberg, who will go on to Japan and China, said Beijing understands "that rebuilding trust here in South Korea is a critical first step towards being able to move forward to a more broad-based dialogue".

Hu and Obama had called for "necessary steps" to restart the six-nation talks which the North abandoned in April 2009, a month before its second nuclear test.

The North has expressed conditional willingness to return. But the United States, South Korea and Japan say it must first mend ties with the South and show it is serious about scrapping its nuclear arsenal.