Russia said Friday it still had "a number of substantial" differences with North Korea concerning efforts to resume stalled six-party negotiations on the Stalinist state's nuclear weapons drive.

Deputy Prime Minister Igor Morgulov's comments after his talks Thursday with Pyongyang's main nuclear negotiator Kim Kye-Gwan suggest that no breakthrough was achieved at the negotiations.

"A number of substantial differences remain," Morgulov told Russian news agencies.

"The positions (of Russia and North Korea) for the moment diverge," he said without giving further details.

Kim held separate talks lasting a reported five hours with Morgulov and First Deputy Foreign Minister Vladimir Titov.

Morgulov said Friday that the sides "reaffirmed their mutual desire to find a diplomatic solution to the existing Korean peninsula problem and discussed various options for relaunching the six-party talks."

"On the whole, we access this exchange of opinions positively," he added.

Kim has been a key figure in the talks aimed at persuading North Korea to abandon its nuclear programme in exchange for aid and security guarantees.

The negotiations began in 2003 but have long been dormant. The six-party process also involves the United States and China as well as South Korea and Japan.

Kim's visit to Moscow came as North Korea reaches out internationally after months of tensions triggered by its third nuclear test in February.

North Korea has said it will never give up its nuclear power but maintains it is open to direct talks with the United States.

Kim last month discussed restarting the six-party talks in Beijing with China's Foreign Minister Wang Yi.