The UN has slapped a global port ban on four vessels found violating sanctions against North Korea, the head of an expert panel said Monday.

"There are four vessels that have been designated by the Committee. The designation doesn't mean an assets freeze or travel ban. But it's a port ban," said Hugh Griffiths, coordinator of the UN Security Council Panel of Experts on North Korea sanctions, adding the ships were found "transporting prohibited goods."

"It's a pretty swift and decisive action by the Committee," he added.