A threat from North Korean Foreign Minister Ri Yong Ho of the possibility of testing a powerful hydrogen bomb over the Pacific Ocean should be taken literally, a senior Pyongyang official told CNN in an exclusive interview.

The official, Ri Yong Pil, told CNN on Wednesday here that the threat should not be dismissed.

"North Korea has always brought its words into action," he said.

The Foreign Minister made the threat last month while visiting New York for the UN General Assembly.

The threat came hours after US President Donald Trump threatened to "totally destroy" North Korea in a speech to the UN.

"The Foreign Minister is very well aware of the intentions of our supreme leader, so I think you should take his words literally," Ri Yong Pil told CNN.

North Korea carried out the strongest of its nuclear tests in September, claiming to have used a hydrogen bomb.

The UN responded to the test by imposing fresh sanctions.

Ri Yong Ho
In the picture, The Democratic People's Republic of Korea's (DPRK) Chief nuclear negotiator Ri Yong HoIANS

Ri Yong Pil also implied that diplomatic channels between the US and North Korea were non-existent, despite US Secretary of State Rex Tillerson reiterating over months that they were still open.

"The US is talking about a military option and even practicing military moves. They're pressuring us on all fronts with sanctions. If you think this will lead to diplomacy, you're deeply mistaken."

The official's remarks come after Trump on Sunday boasted that the US was "prepared for anything" when it came to the North Korea nuclear crisis.