SEOUL, South Korea (AP) — South Korea says North Korea has withdrawn its staff from an inter-Korean liaison office in North Korea.

The development came after the second U.S.-North Korea summit talks in Vietnam last month collapsed due to disputes over U.S.-led sanctions on the country.

Seoul's Unification Ministry said Friday that North Korea informed South Korea of its decision during a contact at the liaison office at the North Korean border town of Kaesong.

The ministry calls the North's decision "regrettable."

It says the North didn't give a specific reason for its move.

The liaison office opened last September as part of a flurry of reconciliation steps.