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South Korea's president said Tuesday that North Korea is showing no sign of giving up nuclear weapons, although the communist regime has made recent conciliatory gestures because U.N. sanctions against it are working.

In a joint interview with South Korea's Yonhap news agency and Japan's Kyodo news agency, conservative President Lee Myung-bak also accused the North of trying to win economic aid while holding on to atomic weapons.

He urged other members of the stalled six-nation talks with North Korea to "redouble efforts" to rid the North of nuclear weapons.

Lee's remarks came as the United States is preparing to accept North Korea's offer to hold direct talks, and they underline his deep skepticism about a neighbor that is abruptly taking a softer line following nuclear and missile tests just a few months ago.

"It appears to be true that North Korea is fairly embarrassed because of greater than expected real effects" of U.N. sanctions, Lee said, according to a published Yonhap transcript. Lee's office confirmed its contents.

"North Korea is using some conciliatory strategy toward the United States, South Korea and Japan in order to get out of this crisis, but for now, North Korea is not showing any sincerity or sign that it will give up nuclear weapons," he said.

North Korea pulled out of talks with the U.S., South Korea, China, Russia and Japan in April, protesting international criticism of its launch of a rocket that other nations suspected was a test of long-range missile technology.

In May, it conducted a nuclear test that drew tough new U.N. sanctions on the North's weapons exports and financial dealings. The sanctions also allow inspections of suspect North Korean cargo in ports and on the high seas.

Amid the sanctions, the North has been taking conciliatory gestures, freeing detained American and South Korean citizens and pledging to resume suspended joint projects and family reunions with South Korea.

The North also has invited Washington's special envoy on North Korea, Stephen Bosworth, to visit Pyongyang for bilateral negotiations that would be the countries' first nuclear talks since President Barack Obama took office.

Over the weekend, the State Department said the U.S. is preparing to accept the offer, but said the talks will be part of efforts to resume the six-nation negotiations.

South Korea has said it does not oppose the direct talks.

Lee said the North's goal with the conciliatory gestures appears to be to "receive economic cooperation while trying to buy time to make it a fait accompli" for it to possess nuclear weapons.

On relations with Japan, Lee said he expects the sensitive ties will improve further with Tokyo's incoming government of Yukio Hatoyama, who is expected to be elected as Japan's next prime minister in a vote in parliament's lower house Wednesday.