BEIJING (AFP) - The US envoy for North Korea on Wednesday hailed a move by a Chinese bank to close the account of a North Korean bank as a meaningful step, amid efforts to tighten sanctions on the North.

"It is a significant development and I think it does help sharpen the choices that Pyongyang faces as it goes forward," Mr Glyn Davies told reporters after a day of meetings with Chinese officials.

Mr Davies was referring to reports last week that state-owned Bank of China shut the account of the Foreign Trade Bank of North Korea, accused by the US of supporting the North's nuclear programme.

"I think China is, in its own fashion, seeking to convey messages to Pyongyang so that they understand the importance that China attaches to denuclearisation," Mr Davies added.

The US, South Korea and Japan have for nearly a decade been working with Russia and China to entice North Korea to abandon its nuclear programme in return for aid and security guarantees.

Despite agreements along the way, the effort has so far been a failure.

North Korea has carried out three underground nuclear tests as well as ballistic missile test-launches.

The most recent nuclear test in February resulted in fresh United Nations sanctions aimed at halting funding for the programme.

"We talked a great deal about what is happening now in North Korea, how we evaluate it and how we might move forward diplomatically with North Korea," Mr Davies said, calling the discussions part of "a long strategic conversation that we're having with the Chinese".

Mr Davies held talks in South Korea before travelling to Beijing and goes on Thursday to Japan.

He avoided commenting in detail on an unexplained and ongoing visit to North Korea by an adviser to Japanese Prime Minister Shinzo Abe.

Mr Abe refused to comment in parliament on Wednesday about the visit, but said he might be willing to meet North Korean leader Kim Jong Un if it could help resolve the issue of Pyongyang's abductions of Japanese citizens.