North Korea 'very serious' about dismantling nuclear weapons: Trump

North Korea is "very serious" about dismantling its nuclear weapons, US President Donald Trump said on Monday, dismissing reports that Pyongyang does not intend to fully surrender its nuclear stockpiles.

North Korean leader Kim Jong-un had pledged to work towards "complete denuclearisation" during a historic meeting with Trump in Singapore on June 12 in return for security guarantees from the US.

The Washington Post reported on Sunday that North Korea was considering ways to conceal its nuclear weapons and secret production facilities.

Responding to the report, Trump said, "I think they (North Koreans) are very serious about it (denuclearisation). I think they want to do -- we had a very good chemistry.

"I made a deal with him. I shook hands with him. I really believe he means it," Trump told Fox news.

The daily, citing intelligence officials, said that the US intelligence officials have concluded that North Korea does not intend to fully surrender its nuclear stockpiles.

Appearing on a different Sunday talk show on CBS News, his National Security Advisor John Bolton said that the US has developed a programme to dismantle North Korea's nuclear weapons.

Secretary of State Mike Pompeo will be discussing with the North Koreans in the near future about really how to dismantle all of their weapons of mass destruction and ballistic missile programs in a year, he said.

"If they have the strategic decision already made to do that, and they're cooperative, we can move very quickly. It's to North Korea's advantage to see these programmes dismantled very quickly, because then the elimination of sanctions, aid by South Korea and Japan and others can all begin to flow.

"We would be able to dismantle the overwhelming bulk of their programmes within a year," Bolton said.

Noting that the US is very well aware of North Korea's pattern of behaviour over decades of negotiating with the US, he said that the Trump administration knows exactly what the risks are of them using negotiations to drag out the length of time they have to continue their nuclear, chemical, biological weapon programmes and ballistic missiles.

The president would like to see these discussions move promptly to get a resolution, Bolton said, adding that this has been the advice that China's leader Xi Jinping has given to the US as well.

"So we're going to try and proceed to implement what the two leaders agreed to in Singapore. But rather than have a series of reports, things are going better, things are not going well, they're concealing this, they're not concealing that, really, it doesn't serve the purpose of advancing the negotiations.

"But there's not any starry-eyed feeling among the group doing this, that we're well aware of what the North Koreans have done in the past," Bolton added.

Some US officials believe that North Korea has about 65 nuclear warheads.

Further in addition to the known uranium-enrichment facility, some 96 kms north of Pyongyang, North Korean is also believed to have been operating a secret underground uranium enrichment site known as Kangson, the Post reported.