While the allies both want North Korea to give up its nuclear weapons and end its missile program, they have at times disagreed on the approach, with South Korean President Moon Jae-in keen to build economic ties between the two Koreas while the United States has long insisted on action on denuclearization as a first step.

South Korea's foreign ministry, in a statement on the call between Blinken and Chung, said they had agreed to hold detailed discussions on ways to cooperate with North Korea, including humanitarian cooperation, and continue to make efforts to engage with it.

"The secretary and the minister agreed to continue the coordinated diplomatic efforts [...] to make substantial progress toward the goal of complete denuclearization and establishment of lasting peace on the Korean Peninsula," the ministry said.

Blinken confirmed US support for dialogue and engagement between North Korea and South Korea, the US Department of State said in a statement.

Last week, the two Koreas restored hotlines that North Korea severed a year ago and South Korean officials said Moon and North Korean leader Kim Jong-un were seeking to repair strained ties and resume summits.

According to South Korean lawmakers, North Korea is seeking some easing of international sanctions before it resumes negotiations with the US. But the US has shown little inclination to ease sanctions before talks over North Korea's nuclear weapons and ballistic missiles.

Nevertheless, South Korea officials have been encouraged by a declaration by the Biden administration, which earlier this year concluded a review of North Korea policy, that it would pursue "practical" diplomacy with North Korea.

Blinken planned to call on Southeast Asian counterparts in a virtual meeting later on Friday to fully implement sanctions on North Korea, state department spokesman Ned Price said on Monday.

About 28,500 US troops are stationed in South Korea as a legacy of the 1950-1953 Korean War, which ended with an armistice rather than a peace treaty, leaving the peninsula in a technical state of war.

Meanwhile, more than 1,100 homes in North Korea were damaged, thousands of people evacuated, and farms and roads washed away after days of heavy rains brought flooding, its state media reported.

The reports come as concern grows about damage to crops and the possible impact on food supplies in North Korea, which is cut off from most foreign imports and aid by self-imposed border restrictions aimed at preventing a coronavirus outbreak, as well as by international sanctions.

Heavy rain struck several areas on the east coast, including North and South Hamgyong provinces, state broadcaster KRT reported on Thursday.

Television footage showed homes flooded to their roofs, and bridges and dikes washed away.

The deputy head of the State Hydro-Meteorological Administration, Ri Yong Nam, told the broadcaster that parts of North Hamgyong recorded over 500 mm of rain from Sunday through Tuesday, while areas of South Hamgyong exceeded the average monthly precipitation in those days.

"We expect more rain in August in various regions including the east coast area, which may cause further damage," he said.

In June, leader Kim Jong-un said the country faced a "tense" food situation and much would depend on this year's harvests.

For months, state media have shown work to shore up dikes, and improve ditches, bridges and other infrastructure to try to prevent damage from floods.