Less than two months after a landmark US-North Korea summit in Singapore, US Secretary of State Mike Pompeo has flown back to the city state and says North Korea's continued work on weapons programs was inconsistent with its leader's commitment to denuclearise.

Key points: Mr Pompeo has told Senate North Korea continues to make bomb fuel despite denuclearisation pledge

Mr Pompeo has told Senate North Korea continues to make bomb fuel despite denuclearisation pledge Mr Pompeo thanks ASEAN leaders for enforcing sanctions on North Korea

Mr Pompeo thanks ASEAN leaders for enforcing sanctions on North Korea The US accuses Russia of violating North Korea sanctions

Mr Pompeo was asked en route to Singapore about his statement in the US Senate last month that North Korea was continuing to make bomb fuel and reports that North Korea, led by Kim Jong-un, was building new missiles.

"Chairman Kim made a commitment to denuclearise," Mr Pompeo told reporters on Friday.

"The world demanded that they [North Korea] do so in the UN Security Council resolutions … To the extent they are behaving in a manner inconsistent with that, they are a) in violation of one or both the UN Security Council resolutions and b) we can see we still have a ways to go to achieve the ultimate outcome we're looking for."

In a landmark summit with US President Donald Trump in Singapore on June 12, Mr Kim, who is seeking relief from tough sanctions, committed in a broad statement to work toward denuclearisation, but Pyongyang has offered no details as to how it might go about this.

Mr Pompeo told a Senate committee hearing on July 25 that North Korea was continuing to produce fuel for nuclear bombs in spite of its pledge.

On Monday, a senior US official said US spy satellites had detected renewed activity at the North Korean factory that produced the country's first intercontinental ballistic missiles capable of reaching the United States.

The Washington Post reported on Monday that North Korea appeared to be building one or two new liquid-fuelled intercontinental ballistic missiles at the research facility, citing unidentified officials familiar with intelligence reporting.

Mr Pompeo thanked ministers of the Association of Southeast Asian Nations (ASEAN) at a meeting in Singapore for their efforts in enforcing sanctions on North Korea.

Russian bank punished

The United States on Friday imposed sanctions on a Russian bank it said had facilitated a transaction with a person blacklisted by Washington for involvement with North Korea's nuclear weapons program.

The US Treasury Department said Moscow-based Agrosoyuz Commercial Bank had conducted "a significant transaction" for Han Jang Su, the Moscow-based chief representative of Foreign Trade Bank, North Korea's primary foreign exchange bank.

"The United States will continue to enforce UN and US sanctions and shut down illicit revenue streams to North Korea," US Treasury Secretary Steven Mnuchin said in a statement.

Commenting on the new US sanctions, Russian Deputy Foreign Minister Sergei Ryabkov said US attempts to pressure Russia do not work.

The United States has also asked the United Nations Security Council North Korea sanctions committee to mirror its new sanctions and blacklist the Russian bank, a Moscow-based North Korean banker and two front companies for Pyongyang's primary foreign exchange bank.

The 15-member Security Council committee has to agree such requests by consensus.

The council blacklisted North Korea's primary foreign exchange bank, the Foreign Trade Bank, in August last year.

Reuters