"Talks between senior South Korean diplomat Vee Son Nak and Russian Deputy Foreign Minister Alexei Borodavkin be held tomorrow afternoon in the Ministry," the source said on Wednesday.

South Korea's 1,200-ton Cheonan corvette sank near the disputed Northern Limit Line in the Yellow Sea on March 26, causing the loss of 46 lives. An international investigation revealed that North Korea fired a torpedo at the vessel from a submarine, although Pyongyang has denied the allegations.

South Korea has frozen economic relations and maritime communications with its northern neighbor, further crippling the North's economy, which is already damaged by UN sanctions intended to force it to quit its nuclear program.

North Korea retaliated by announcing it was cutting all ties with Seoul and allegedly ordered its 1.2-million-man armed forces to get ready for combat. It later announced the withdrawal of all its military safeguards in relations with the South and said it would scrap an agreement between the two countries aimed at preventing clashes off the west coast.

Vee Son Nak said on Wednesday Seoul was seeking an agreement from Russia to take the Cheonan issue to the UN Security Council.

South Korea wants a resolution from the UN Security Council condemning North Korea and demanding an apology, rather than new sanctions. However, press reports have suggested that if China speaks against the request, the UN Security Council will only be able to issue a statement by its chairman.

Vee Son Nak and Borodavkin headed the South Korean and Russian delegations at the Six-Party Talks in Beijing on North Korea's Nuclear Program. In April 2009, North Korea halted the talks in protest to the UN Security Council's condemnation of its missile tests.