They also agreed to arrange a US visit for Suga as early as possible, Suga told reporters.

The White House said the two affirmed the importance of the US-Japan alliance "as the cornerstone of peace and prosperity in a free and open Indo-Pacific".

They two sides said they also reconfirmed that the US-Japan security treaty applied to a group of Japan-controlled East China Sea islets that China claims, called the Senkaku in Japan and Diaoyu in China.

Biden reaffirmed too the US commitment to provide "extended deterrence" to Japan, a reference to the US nuclear umbrella covering Japan, the White House said in a statement.

The two leaders affirmed the necessity of complete denuclearisation of the Korean Peninsula, it added.

"We managed to have substantial exchanges," Suga said.

"We agreed to strengthen our alliance firmly by having more phone calls like this."

Shortly after his Senate confirmation on Tuesday, Biden's new secretary of state, Antony Blinken, spoke to both his South Korean and Japan counterparts and emphasized Biden's commitment to strengthening the US alliances with both countries.

Blinken also stressed the need for continued trilateral co-operation among the allies.

Australian Associated Press