SEOUL - South Korea's presidential office expressed regret after the summit between United States President Donald Trump and North Korea's Kim Jong Un ended without a deal, but said "meaningful progress" had been made.

"It is regrettable President Trump and North Korean leader Kim Jong Un did not reach a complete agreement on today's summit," Blue House spokesman Kim Eui-kyeom said in a statement on Thursday (Feb 28).

"But it appears clear that more meaningful progress was made than at any other point in the past," he was quoted as saying by Agence France-Presse.

The spokesman said the meeting may have allowed the two leaders to better understand each other, raising the possibility of a breakthrough in the future, reported Yonhap news agency.

"Also, the willingness expressed by President Trump to hold continued dialogue and his optimistic view offer a bright prospect for the next meeting," Mr Kim said.

"The fact that President Trump publicly mentioned the possibility of removing or easing sanctions in connection with North Korea's denuclearisation steps is an important occasion that shows the discussions between the North and the US have been elevated," he added.

The spokesman expressed hope for continued dialogue between the US and North Korea, Yonhap reported.