A second summit between U.S. President Donald Trump and North Korean leader Kim Jong Un, in Vietnam, was cut short after they failed to reach a deal on the extent of sanctions relief North Korea would get in exchange for steps to dismantle its nuclear programme.

South Korea's President Moon Jae-in has been an active supporter of efforts to end confrontation on the Korean peninsula, meeting Kim three times last year and trying to facilitate his nuclear negotiations with the United States.

"My administration will closely communicate and cooperate with the United States and North Korea so as to help their talks reach a complete settlement by any means," Moon said in a speech in the South Korean capital, Seoul.

Read: Trump, Kim Jong Un End Vietnam Summit with No Agreement

Moon also said South Korea would consult with the United States on ways to resume joint projects with the North including tourism development at Mount Kumgang and the Kaesong industrial complex, both in North Korea.

The Hanoi summit came eight months after Trump and Kim met for the first time in Singapore and agreed to establish new relations and peace in exchange for a North Korean commitment to work toward complete denuclearisation of the Korean peninsula.

Trump said two days of talks had made good progress but it was important not to rush into a bad deal. He said he had walked away because of unacceptable North Korean demands.

"It was all about the sanctions," Trump told a news conference after the talks were cut short. "Basically, they wanted the sanctions lifted in their entirety, and we couldn't do that."

REUTERS