A US top official has accused Iran and North Korea of trying to obtain high-tech materials linked to their armament programs, despite UN sanctions obstructing direct supplies.

"Both Iran and North Korea have developed channels that enable them to continue to export and continue to procure the items they need for their weapons industry," said Thomas Countryman, the US's Assistant Secretary for International Security and Nonproliferation.

Countryman stressed that such activity by Iran and North Korea violates UN sanctions that are banning them from the acquisition of nuclear, missile and related high-tech or any other military materials, as well as the export of such items.