UNITED NATIONS (AFP) - The UN Security Council on Thursday (Dec 28) denied international port access to four North Korean ships suspected of carrying or having transported goods banned by international sanctions targeting Pyongyang, diplomats said.

The ban of the four vessels - the Ul Ji Bong 6, Rung Ra 2, Sam Jong 2 and Rye Song Gang 1 - was requested by the United States along with measures targeting ships registered in other countries, they said on condition of anonymity.

But China only agreed to target the four North Korean ships, diplomats said, as part of international efforts to curb Pyongyang's missile and nuclear programmes.

"Only four ships have been accepted" for the ban, but "the procedure remains open" to include other vessels in the future, one diplomat said.

The list submitted by the US in December had also included ships flying flags from Belize, China, Hong Kong, Palau and Panama.

In 2017, the Security Council has slapped three sets of sanctions on North Korea: one on Aug 5 targeting the iron, coal and fishing industries; another set on Sept 11 aimed at textiles and limiting oil supply; and the most recent on Dec 22 focused on refined petroleum products.

The US has denounced trafficking of banned goods that allows North Korea to stock up, particularly the transfer of cargo between different ships on the high seas.

Blocking suspected vessels from ports - except in the case of humanitarian need as determined by the council's sanctions committee - is provided for in the August resolution.

On Oct 5, the UN had already identified four ships "carrying prohibited goods", resulting in a ban on port access that was a "first in United Nations" history, according to Mr Hugh Griffiths, part of a UN panel of experts monitoring the application of sanctions on Pyongyang.

Those four vessels were registered in the Comoros, Saint Kitts and Nevis, Cambodia and North Korea, and were targeted for the illegal transport of coal, iron and North Korean fish.