SEOUL - Planned high-level talks between North and South Korea - the first for six years - were called off at the last minute Tuesday, because of a dispute over the status of their respective chief delegates.

The rift over a matter of protocol was a stark example of the trust deficit that still dominates relations 60 years after the end of the Korean War. A N Korean delegation had been scheduled to cross the heavily-militarised border on Wednesday and drive down to Seoul for the two-day talks in the Grand Hilton Hotel. Although no major breakthroughs were expected, the meeting had been seen as an opportunity to improve relations after months of dangerously inflated tensions and threats of nuclear war.

S Korean Unification Ministry spokesman Kim Hyung-Seok said Pyongyang took the decision to cancel after it objected to Seoul nominating a vice-minister to head its team.

“North Korea, taking issue with the level of our chief delegate, unilaterally told us that it was postponing the dispatch of its delegation,” Kim said. There was no immediate statement from North Korea and it was not clear if the postponement was meant to be temporary or indefinite.

According to Kim, the North had complained that naming a vice-minister made a “mockery” of the talks’ importance and contravened what had been agreed at a preparatory meeting on Sunday. South Korea regretted the North’s decision, Kim said, while adding that it defied “common sense”. On the proposed talks agenda was the resumption of two suspended commercial projects, including the Kaesong joint industrial complex which the North shut down in April as the recent crisis peaked.

Whatever the outcome, the fact that the talks were to happen at all had been taken as a positive sign in the circumstances.

North Korea’s third nuclear test in February and a subsequent tightening of UN sanctions had triggered a sharp surge in military tensions that lasted more than two months.

At their height, Pyongyang was threatening pre-emptive nuclear strikes and the United States was sending nuclear-capable stealth bombers to take part in joint military exercises with the South.

Then, in a complete reversal, North Korea last week proposed opening a dialogue.

Working-level talks followed in the border truce village of Panmunjom on Sunday and the high-level meeting was set for Wednesday and Thursday in the South Korean capital.

But right from the start there was disagreement over who precisely would lead the talks and what would be on the agenda.

South Korea had initially suggested that the talks be headed by its pointman on North Korea, Unification Minister Ryoo Kihl-Jae, and his counterpart in Pyongyang, Kim Yang-Gon.

North Korea rejected the idea, although it insisted that the chief delegates should be of “minister-level”.

“This whole episode just shows how deep the mistrust between the two sides really runs,” said Professor Yang Moo-Jin of the University of North Korean Studies in Seoul.

The move towards dialogue had been broadly welcomed on the Korean peninsula and beyond, but there was always substantial scepticism about Pyongyang’s intentions.

Some analysts had suggested the North was paying lip-service to the idea of talks to coincide with the weekend summit between US President Barack Obama and Chinese President Xi Jinping.

China, the North’s sole major ally and economic benefactor, has been under US pressure to restrain its neighbour and has pushed Pyongyang to engage in dialogue rather than seek confrontation.

As well as Kaesong, the two sides had been scheduled to discuss resuming South Korean tours to the North’s Mount Kumgang resort and the reunion of families divided by the Korean War.

Kaesong and Mount Kumgang were both significant sources of scarce foreign currency for North Korea, which is increasingly feeling the squeeze of UN sanctions.