In a speech to mark South Korea's liberation from Japanese colonial rule 58 years ago, Roh expressed optimism the August 27-29 talks in Beijing could lead to a breakthrough in the stand-off.

"Luckily, we begin to see signs of a solution to the problem caused by the North's nuclear program," Roh said. "North Korea should not miss this opportunity."

The United States, Japan, China, Russia and the two Koreas have agreed to take part in the talks after weeks of wrangling over a dialogue format.

The South Korean leader said if North Korea dropped its nuclear ambitions, South Korea would help the communist state rebuild its devastated economy.

"It must dismantle its nuclear program and open itself up successfully. Nuclear weapons can never become a shield to protect its system. On the contrary, the program will cause further isolation and crisis."

He renewed his call for a peaceful end to the stand-off and called for an early settlement.

"The North Korean nuclear issue should be resolved as early as possible. It has to be settled peacefully at all costs," he said.

The nuclear crisis erupted in October last year when the United States accused Pyongyang of reneging on a 1994 bilateral nuclear accord by setting up a clandestine program based on enriched uranium.

North Korea responded by kicking out UN nuclear inspectors and withdrawing from the treaty. It has since claimed to have reprocessed 8,000 spent fuel rods at its nuclear plant at Yongbyon.

Roh did not elaborate on what Pyongyang would get in return for giving up its nuclear ambitions, but hinted at economic rewards.

"We will collaborate with our neighbors in an endeavor to induce the cooperation of international organizations as well as international capital for the North," he said in a Liberation Day speech.

In the speech at the independence memorial hall in Cheonan, 90 kilometers (55 miles) south of Seoul, Roh described the 1910-45 Japanese colonial rule of Korea as a "humiliating" chapter of history that Korea must not allow to be repeated.

He vowed to boost the country's defense, while stressing a need to gradually reduce heavy reliance on the United States.

"The country has emerged as the 12th largest economy in the world. It is about time we took responsibility for defending ourselves," he said.

But he said such efforts should not undermine the current South Korea-US military alliance.

Hours later in downtown Seoul, thousands of South Koreans marked the anniversary of the Liberation Day with two different sets of rallies for and against North Korea over its nuclear ambitions.

Some 9,000 people, including student activists, marched calling for "National Unity" with North Korea and denouncing what they call the US hostile policy on Pyongyang.

Just several blocks away, more than 5,000 conservatives, including Christians and military veterans, were holding a separate anti-North Korean rally to condemn Pyongyang's leader Kim Jong-Il and its nuclear program.

Meanwhile, the United States named Assistant Secretary of State for East Asia and Pacific Affairs James Kelly Thursday to head its delegation to the new six-way nuclear crisis talks.

Kelly on Thursday met his South Korean and Japanese counterparts in Washington to hone their positions as part of the flurry of diplomacy ahead of the multilateral talks.

WAR.WIRE