Deputy foreign minister Song Min-Soon and presidential security advisor Kwon Jin-Ho were to meet US officials to prepare for summit and "have consultations on North Korea's nuclear issue," the foreign ministry said here.

Roh is expected to meet President George W. Bush on June 10 to discuss "the way forward on North Korea," White House spokesman Scott McClellan has said.

Roh is also seeking a meeting in June with Japanese Prime Minister Junichiro Koizumi to discuss North Korea, among other issues, the South Korean foreign ministry said.

The Roh-Bus summit comes almost one year after the last round of six-nation talks on the standoff were held in Beijing. The talks involve China, Japan, Russia, the United States and the two Koreas.

The impasse over North Korea's nuclear weapons programme shows no signs of easing, with Washington and Pyongyang stepping up verbal attacks against each other.

US Vice President Richard Cheney on Sunday called North Korean ruler Kim Jong-Il an "irresponsible" leader who "doesn't take care" of his people while he pushes for nuclear power status.

Aside from what Pyongyang cites as a US "hostile policy," attacks on Kim and the communist state by Bush and other US officials have been a major contributing factor to the breakdown in the nuclear disarmament talks.

Pyongyang has said Washington must apologize for publicly branding Kim a "tyrant" and their country "an outpost of tyranny," but Cheney made clear it should not expect any softening of the US tone, let alone an apology.

North Korea raised the stakes by declaring in February it had nuclear weapons and claiming it had unloaded 8,000 spent fuel rods from its reactor that could be reprocessed into weapons-grade plutonium.

It has however denied reports that it is preparing to conduct a nuclear test, according to a Czech parliamentary delegation that visited Pyongyang last week.