US President Donald Trump said Wednesday he will not be meeting with North Korean leader Kim Jong-un on his trip to Asia this week but may speak to him "in a different form."

Trump made the remarks as he left the White House for Osaka, Japan, where he will attend the Group of 20 summit before traveling to South Korea on Saturday.

"I'll be meeting with a lot of other people, not by him, but I may be speaking to him in a different form," Trump said.

"I'll be going, as you know, to South Korea after we're finished with the G20. And we'll be there for about a day. We have a lot of meetings planned with a lot of different countries," he said.

Trump did not elaborate on how he could speak to the North Korean leader.

There was speculation earlier that during his trip to South Korea on Saturday and Sunday he could travel to the Demilitarized Zone on the inter-Korean border and meet with Kim there.

A senior US official told reporters on Monday, however, that there are no plans for a Trump-Kim meeting on the peninsula. On a possible DMZ trip, he said he couldn't confirm it because the president's schedule was still being finalized.

Trump will hold talks with President Moon Jae-in on North Korea's nuclear weapons program, the South Korea-US alliance, and the bilateral trade relationship, according to officials.

Moon, who has been credited with resuming diplomacy with the isolated regime last year, will likely seek to bridge the gap between North Korea and the US on how to match denuclearization steps with sanctions relief.

Trump and Kim agreed at their historic first summit last June to work toward complete denuclearization of the Korean Peninsula in exchange for US security guarantees.

But a second summit in February ended without a deal, leading to a monthslong lull in negotiations and renewed tensions over North Korea's tests of short-range missiles in May.

This month saw an exchange of personal letters between Trump and Kim, which has raised hopes for a fresh round of talks.

Moon said in a written interview Wednesday with Yonhap News Agency and six other global news agencies that North Korea and the US have been in talks over a third summit. (Yonhap)