Japan and China agreed Sunday to resume reciprocal visits by their leaders, with Asia's two biggest economies eager to mend ties in the year marking the 40th anniversary of the signing of a bilateral friendship treaty.

But the two sides apparently failed to find common ground over sensitive issues, including a territorial dispute, underscoring the need for them to focus on the momentum toward improvement in their relations.

Japanese Foreign Minister Taro Kono said he asked Chinese Premier Li Keqiang during their talks in Beijing to visit Japan as soon as possible to participate in a postponed trilateral summit including South Korea, which Tokyo wanted to host last year. Kono said Li replied to the request "in a positive manner."

If realized, the summit would bring Li to Japan for the first time since he took office in 2013.

Earlier in the day, Kono also met with his Chinese counterpart Wang Yi and State Councilor Yang Jiechi, the nation's top diplomat.

During their more-than-three-hour talks, Kono and Wang confirmed the importance of mutual visits by their leaders for the full-fledged reconciliation of the two countries, a Japanese government official said.

"We want to improve overall (bilateral) ties this year," Kono, the first Japanese foreign minister to visit China in about two years, said at the outset of the meeting open to the media.

Kono, who arrived in Beijing on Saturday, noted the significance of this year as Japan and China mark the 40th anniversary of the signing in 1978 of the Treaty of Peace and Friendship between the two nations.

Wang responded to Kono by saying Beijing welcomes Tokyo's "strong determination" to improve bilateral relations, while Yang told Kono that he "enthusiastically" welcomes the Japanese foreign minister's visit to China.

All the meetings were held "in a positive and bright atmosphere," Kono told reporters.

Japanese Prime Minister Shinzo Abe and Chinese President Xi Jinping have yet to exchange official visits due in part to the row over the Tokyo-controlled Senkaku Islands, a group of uninhabited islets in the East China Sea that Beijing claims.

Tokyo and Beijing have been mired in a territorial row over the Senkakus, called Diaoyu in China, for years. The dispute escalated particularly after the Japanese government led by then Prime Minister Yoshihiko Noda, Abe's predecessor, decided to effectively put them under state control in September 2012.

Bilateral relations, however, appear to be improving after both Abe and Xi bolstered their domestic power bases late last year through key political events at home.

An increasing number of policymakers and scholars from Japan and China believe that the renewed political stability in each country would create a better environment to promote practical cooperation.

Kono said North Korea's ballistic missile and nuclear ambitions were also on the agenda during the meetings, as Japan has asked China to exercise leverage over Pyongyang and play a key role in forcing the nation to change its policy.

Japan and China agreed to continue working together to realize denuclearization of the Korean Peninsula, Kono said, adding the two countries confirmed they "won't accept" Pyongyang as a nuclear power.

Meanwhile, Kono lodged a protest over the entry of a submerged Chinese submarine into the contiguous zone around Japanese territorial waters near the Senkakus earlier this month, urging Beijing to take preventive steps.

Kono and Wang agreed to make efforts for the early implementation of a "Maritime and Aerial Communication Mechanism" in the East China Sea, where China challenges the sovereignty of the Senkakus.

Japan called on China to avoid taking actions that could escalate tensions in the East China Sea, Kono said, adding China repeated its "own assertiveness" on the maritime issue.

"There are concerns between the two countries as we are neighbors," Kono said. "But as the world's second- and third-largest economies...we will manage them in a way that would not hurt friendly Japan-China ties."

In a sign that relations between Japan and China are improving, the two nations reached an effective accord on a bilateral social security agreement that would eliminate dual pension payments by Japanese expats in China and vice versa.

Kono's trip to China is the first by a Japanese foreign minister since his predecessor Fumio Kishida visited in April 2016. He is slated to return to Tokyo early Monday.