North Korean leader Kim Jong-un and US President Donald Trump agreed to continue "productive dialogues" to resolve issues raised at their second summit in Hanoi, Pyongyang's official news agency said Friday, a day after the talks ended without a written agreement.

The Korean Central News Agency also said the summit served as an important chance to deepen mutual respect and trust.

"They agreed to keep in close touch with each other for the denuclearization of the Korean peninsula and the epochal development of the DPRK-US relations in the future, too, and continue productive dialogues for settling the issues discussed at the Hanoi summit," the KCNA said, referring to the North by its official name.

Kim "expressed his thanks to Trump for making positive efforts for the successful meeting and talks while making a long journey and said goodbye, promising the next meeting," it said.

The report, however, made no mention of the summit ending Thursday without a signed agreement or declaration.

Following the two-day talks Thursday, Trump said Pyongyang demanded Washington lift sanctions "in their entirety," which he couldn't accept.

North Korean officials later refuted that, claiming they just asked for partial sanctions relief in exchange for dismantling its key Yongbyon nuclear complex.

North Korean Vice Foreign Minister Choe Son-hui said leader Kim "may have lost his enthusiasm for a deal between the North and the US down the road."

The summit was widely expected to be focused on discussing concrete denuclearization steps North Korea could take and "corresponding" reciprocal concessions the US could provide in return, such as easing sanctions.

The Hanoi meetings came eight months after Kim and Trump held their first-ever summit in Singapore last June that committed the two to the complete denuclearization of the Korean Peninsula.

The June summit has been criticized often for being long on promises but short on specifics. (Yonhap)