The six nations concluded their second-day talks aimed to denuclearize the Korean Peninsula Wednesday with no evident progress in narrowing their differences.

China, the Democratic People's Republic of Korea (DPRK), the United States, the Republic of Korea (ROK), Russia and Japan, held a plenary session in the morning, followed by bilateral meetings.

No result was achieved in the six-party talks on Wednesday, the second day of the event, said Russian delegation head Alexander Alexeyev.

"There are still substantial and even conceptual differences between the DPRK and the United States," Alexeyev, also deputy foreign minister of Russia, was quoted by the Interfax as saying.

"One of the issues talked about was the issue of highly enrichment of Uranium," said the US official. "We did not achieve an agreement with them. But we did agree to keep talking about that."

The US official said there are still fundamental differences among the parties.

On the other hand, the top DPRK negotiator, Kim Kye-gwan, has reportedly said his country will never dismantle its nuclear program unless it gets full US diplomatic recognition.

He also demanded the removal of a US nuclear umbrella for South Korea, a legacy of the 1950-53 Korean War, the ROK news agency Yonhap quoted sources as saying.

"Our goal is to get rid of US nuclear threats to us and make the Korean Peninsula free of nuclear weapons," Kim was quoted as saying. "It is necessary that the US promise to end its hostility and ensure a peaceful coexistence with our country legally and with a system."

The US official said the US and the DPRK will hold another one-on-one meeting on Thursday, which Russian delegation head Alexander Alexeyev said may influence the result of the six-party talks to a large extent.

He said that all the six parties remained cautiously optimistic about the current round of the talks.

Chinese delegation head Wu Dawei on Wednesday called on all sides to seize opportunities, meet challenges and work together with their "utmost political courage" to create a better future for Northeast Asia.

The ROK delegation proposed that "two pillars" should be set upin seeking a solution to the Korean nuclear issue.

An official, unwilling to reveal his name, said the proposal was made by Song Min-soon, head of the ROK delegation and deputy foreign minister of the nation, in a keynote speech when addressing the plenary meeting in the morning.

Song was quoted as saying that this round of talks should result in a common document such as a common declaration.

The "two pillars," which should be included in the common document, refer to the promise on the DPRK to give up its nuclear program and the promise of the other parties to normalize their relations with the DPRK, provide a security guarantee and economic cooperation.

The ROK delegation said the common document should take "words for words and action for action" as a precondition and all the sides should carry out the measures they have agreed on in order to show the principle of "acting simultaneously."

Japan will closely cooperate with the other five countries with a constructive attitude in the talks, Japanese delegation head Sasae Kenichiro said on Wednesday in his keynote speech at the plenary session.

"As for the DPRK promise to scrap its nuclear programs, we will pledge to provide 'security guarantee' for the nation," Sasae said. "In regard to energy aid, we appreciate the 'important proposal' (to provide 2 million kwh of electricity to the DPRK) raised by the government of the ROK."