US President Donald Trump says he is launching the "largest ever" set of new sanctions against North Korea.

The measures will target more than 50 ships and maritime transport companies.

"Today I am announcing that we are launching the largest-ever set of new sanctions on the North Korean regime," Mr Trump said in sections of a speech released in advance.

North Korea is already under a range of international and US sanctions over its nuclear programme and missile tests.

"The treasury department will soon be taking new action to further cut off sources of revenue and fuel that the regime uses to fund its nuclear programme and sustain its military by targeting 56 vessels, shipping companies, and trade businesses that are assisting North Korea in evading sanctions," Mr Trump says.

The US treasury department lists one individual and 27 companies.

Sixteen, mainly shipping companies, are based in North Korea, but five are registered in Hong Kong, two on the Chinese mainland, two in Taiwan, one in Panama and one in Singapore.

Twenty-eight ships are on the list, again mostly North Korean, but two are Panama-flagged, one from the Comoros and one Tanzania-flagged.

The US has been building sanctions against the regime since 2008 and the latest restrictions could come on top of sanctions announced in November - directed at North Korean shipping operations, as well as Chinese companies trading with Pyongyang.

The United Nations followed that up in December with a raft of sanctions, backed by all 15 members of the Security Council, which included measures to cut North Korea's petrol imports by up to 90%.

Read more on bbc.com.