Japan and South Korea must cooperate to counter any threat from North Korea, Japan's new Prime Minister, Yoshihide Suga, told South Korea's president on Thursday, calling for the uneasy neighbors to repair their frayed ties.

Relations between the two US allies have deteriorated sharply over the past year over war-time history and trade, in particular the issue of Korean laborers forced to work at Japanese firms during Japan's 1910-45 colonial rule.

"I told President Moon that we cannot leave our current very difficult relations where they are now," Suga told reporters after a telephone call with South Korea's President Moon Jae-in.

South Korea had asked for the telephone call, Japan said.

Reuters