US Secretary of State Mike Pompeo said Wednesday that Washington is committed to cooperating with North Korea to achieve peace on the Korean Peninsula, according to news reports.

He made the remarks in a lunch meeting with Kim Yong-chol, head of the North's United Front Department handling inter-Korean relations. Pompeo earlier arrived in Pyongyang to discuss details of a summit between North Korean leader Kim Jong-un and US President Donald Trump.

"For decades, we have been adversaries. Now we are hopeful that we can work together to resolve this conflict, take away threats to the world and make your country have all the opportunities your people so richly deserve," Pompeo was quoted as saying by Reuters, citing a pool report.

During the meeting at Pyongyang's Koryo Hotel, Pompeo also said there are still "many challenges along the way," but he added, "You have been a great partner in working to make sure our two leaders will have a summit that is successful."

Kim expressed "high expectations the United States will play a very big role in establishing peace on the Korean Peninsula."

Pompeo responded, "(The US is) equally committed to working with you to achieve exactly (that)."

Kim also said that from now on, the North would concentrate all its efforts into the country's "economic progress," according to the Washington Post. Kim was also quoted as saying the current conciliatory mood is "not a result of sanctions that have been imposed from outside."

Pompeo's visit to Pyongyang was his second in just over a month as US President Donald Trump prepares to hold an unprecedented summit with North Korean leader Kim Jong-un in late May or early June.

Besides discussing details of the summit, including finalizing its date and venue, Pompeo is expected to return to the US with three American citizens being held in the North.

Earlier, an official from Seoul's presidential office Cheong Wa Dae said that the North will likely free the three American detainees soon. (Yonhap)