South Korean President Moon Jae-in and President Donald Trump spoke by phone on Sunday and exchanged views on making the upcoming US-North Korea summit a success, the presidential office said.

The two leaders talked from 11:30 a.m. to 11:55 a.m. and agreed to work together closely on the historic meeting, Cheong Wa Dae said. Moon is scheduled to hold talks with the US chief executive on Tuesday in Washington.

He will return home early Thursday after his two-day trip.

"The two leaders exchanged opinions on various actions taken by North Korea recently," Yoon Young-chan, the senior press secretary to President Moon Jae-in, said in a statement.

Sunday's call is the 15th phone conversation between the two leaders.

The conversation comes amid the North's threats to call off the US-North Korea meeting. North Korea earlier called the June 12 meeting into question when it slammed ongoing military exercises between South Korea and the US as a provocation and an invasion rehearsal.

The Seoul-Washington meeting, meanwhile, is scheduled three weeks before Trump is due to meet North Korean leader Kim Jong-un in Singapore.

The latter will be a first for the leaders of the two countries, which have maintained a confrontational stance toward each other since the 1950-53 Korean War.

Leaders of the two Koreas have met three times, most recently on April 27 in the truce village of Panmunjom.(Yonhap)