South Korea on Tuesday demanded that North Korea return to the negotiating table, while a dispute deepened over a dam in the North that the South says is dangerous.

The South’s attempts to revive dialogue with its communist rival suffered a setback when the North pulled out of four days of economic cooperation talks due to start in Seoul on Tuesday.

The Pyonyang government blamed “reckless” remarks reportedly made by the South’s Foreign Minister Choi Sung-Hong backing a hardline US stance against the North.

In Seoul, presidential spokeswoman Park Sun-Sook said North-South talks must be continued to underpin the fragile stability on the Korean peninsula and ensure the success of events such as the World Cup co-hosted by South Korea and Japan which starts in less than four weeks.

North Korea only agreed to resume contacts after a visit to Pyongyang last month by a South Korean presidential envoy.

Park said of the cancellation: “Maintaining stability on the Korean peninsula through dialogue and cooperation between South and North Korea is a very important pre-requisite for the economy and national events such as the World Cup.

“In this context, the agreement reached during the envoy’s visit must be implemented without fail. We hope the economic cooperation committee meeting will be held soon.”

The US State Department has also called on North Korea to resume the talks with South Korea. The United States announced last week that it is prepared to accept an offer to send an envoy to reopen dialogue with Pyongyang.

North-South relations have been further complicated by fears that a dam just north of their Cold War frontier could collapse. The dam was expected to be one of the key topics at the Seoul talks.

South Korean engineers are working on flood defences despite the North angrily denying that its Imnam Dam was in danger.

“Our concerns have never dwindled. We’ll take countermeasures as earlier announced,” a construction ministry spokesman in Seoul said.

The ministry warned last week that the dam had been “damaged” and could collapse, unleashing a torrent of water on the river which eventually leads to the South’s capital.

The ministry said it would empty two South Korean dams to prepare for a possible flood.

The Korea Water Resources Corporation, which is affiliated to the ministry, said the slopes of the Peace Dam just south of the border would be reinforced with concrete by the end of June so it could withstand a massive surge of water.

Dozens of trucks have been mobilized in the campaign to build new roads to the Peace Dam about 120 kilometers (75 miles) northeast of Seoul.

On Monday, the North’s land and environmental protection ministry spokesman accused the South of issuing a “sheer lie” over the Imnam Dam.

“The security of the dam is fully guaranteed, both in scientific and technological aspects, as it was built as the strongest dam structure in the history of hydraulic power station construction,” he said.

The two Koreas have remained technically at war since fighting the 1950-53 conflict, which ended in an armistice, not a peace treaty.