Japan and China on Saturday agreed they will operate their defense hotline properly, amid disagreements over Taiwan and intrusions by Chinese vessels into waters near the Tokyo-controlled, Beijing-claimed Senkaku Islands in the East China Sea.

Japanese Defense Minister Yasukazu Hamada told reporters after meeting with his Chinese counterpart Li Shangfu in Singapore that he also expressed his "grave concerns" to Li over China and Russia's continuous joint military activities around Japan.

Japanese Defense Minister Yasukazu Hamada (R) and his Chinese counterpart Li Shangfu hold talks in Singapore on June 3, 2023. (Kyodo)

The hotline between senior defense officials of Tokyo and Beijing began operating last month with the aim of building mutual trust and avoiding contingencies at sea and in the air.

The two countries originally agreed to open the hotline in 2007 as a pillar of the Maritime and Aerial Communication Mechanism that Tokyo and Beijing eventually launched in 2018.

During the 40-minute talks, Hamada and Li vowed to promote further dialogue and exchange between their defense authorities, according to the Japanese Defense Ministry.

As for Taiwan, Hamada said he underscored "the importance of peace and stability across the Taiwan Strait."

Li told Hamada at the meeting, part of which was open to the media, that Japan should not "send an erroneous message to the pro-independence force in Taiwan" and should not "meddle with the Taiwan issue."

China regards Taiwan, a self-ruled democratic island, as a renegade province to be united with the mainland, by force if necessary.

The talks came after the Group of Seven leaders called for a peaceful resolution of cross-strait issues at their summit in Hiroshima last month.

The G-7's concerns about growing Chinese military pressure on Taiwan have been rejected by Beijing as interference in its internal affairs.

In Saturday's meeting, Hamada said, "It is important to keep working hard to build constructive and stable relations," and that there are "many security concerns" between the two countries, including issues involving the Senkakus.

Li said he will contribute to the "long-term development of China-Japan relations."

The meeting also took place after North Korea, which has been accelerating its nuclear and missile activities, attempted to launch a spy satellite on Wednesday, the first day of a pre-declared launch window through June 11, but failed.

Pyongyang said the rocket experienced issues, and pledged to make another attempt "as soon as possible."

Hamada said he strongly condemned the North for going ahead with a launch that used ballistic missile technology. If such technology was used, it would violate U.N. Security Council resolutions aimed at curbing Pyongyang's nuclear and missile programs.

Hamada and Li met on the sidelines of the Asia Security Summit, an annual regional security forum also known as the Shangri-La Dialogue.