South Korea says high-level talks will not take place as scheduled with North Korea in Seoul on Wednesday.
The two sides agreed on Monday to the two-day talks, which had been expected to focus primarily on joint economic projects.
But on the eve of the meeting, officials in Seoul said the two sides were unable to agree on the composition of their delegations.
It was not immediately clear whether the talks, scheduled to take place at a hotel in Seoul, had been postponed or cancelled.
The last time the two Koreas held high-level talks was more than five years ago.
Relations have been tense since a nuclear test by the North on 12 February.
