North Korea was supposed to have provided an inventory of its fissile material and nuclear weapons by the end of 2007, under a disarmament-for-aid deal reached with regional powers.

US Assistant Secretary of State Christopher Hill's visit to Moscow comes after a tour of Asia to discuss the deal, which would award fuel oil or aid for making a full declaration and taking apart its nuclear facilities.

'We can confirm that Christopher Hill will be here today,' said a spokesman for the US embassy in Moscow.

She said he would meet Russian officials on the six party talks on North Korea - a reference to talks which include the two Koreas, the United States, China, Japan and Russia.

Mr Hill would meet Deputy Foreign Minister Alexander Losyukov, Russia's negotiator on North Korea.

'Christopher Hill has already visited four countries participating in the six-party process. It is very interesting for us to learn his point of view,' Itar-Tass news agency quoted an unidentified Russian diplomat.

On the missed deadline, the diplomat was quoted by Tass as saying: 'Moscow is not going to dramatise the situation. The six-party process can both accelerate and slow down.'

The United States is trying to persuade North Korea to make a complete declaration.

North Korea has said it has accounted for its nuclear arms programme as required, but the US says none of the countries in the six party talks has seen the final declaration.

If North Korea lives up to the deal, the energy starved state would receive 1 million tonnes of heavy fuel oil or equivalent aid and the US would take it off its terrorism black list.

North Korea has been cooperating in disabling its three main nuclear facilities - an ageing reactor, a plant that makes nuclear fuel and another one that turns spent fuel into arms-grade plutonium, US and South Korean officials have said.

The disabling of North Korea's nuclear reactor is a key part a complex nuclear deal struck after years of diplomatic wrangling and Pyongyang's test of a nuclear bomb in late 2006.

Russia has been offering North Korea the prospect of energy deals and a possible write off of billions in Soviet-era debt to persuade it to made compromises over its nuclear programme.

'The second round of denuclearisation, in particular, the decommissioning of the objects in Yongbyon, as well as nuclear research declaration will be discussed at the meeting (with Mr Hill),' Tass quoted the Russian diplomat as saying. -- REUTERS