Japanese Prime Minister Shinzo Abe yesterday called for a peaceful resolution to the South China Sea conflict and pledged Japan's continued support for Asean, as the grouping turns 50 this year.

Speaking after bilateral meetings with Indonesian President Joko Widodo in Bogor, West Java, Mr Abe also said Asean will need Indonesia's leadership to maintain its centrality, as the region confronts issues such as tensions in the South China Sea.

Therefore, "Japan will strongly support President Joko", he said.

Without referring to China's increasing assertiveness in the region, Mr Abe said the South China Sea issue had caught the attention of the international community as it directly affects peace and regional stability.

"We reaffirm the importance of upholding the rule of law and promoting a peaceful resolution, and hence will undertake to work together at the Asean meetings and other international meetings that will be held this year," he added.

Mr Abe was in Indonesia as part of a four-nation tour - which includes stops in the Philippines, Australia and Vietnam - to boost economic and security ties between Japan and countries in the region.

He and Mr Joko yesterday agreed to cooperate on a medium-speed railway that will connect the capital, Jakarta, to Indonesia's second-largest city, Surabaya. They also discussed plans to develop a deep-sea port in the town of Patimban in West Java and the Masela oil and gas block in eastern Indonesia.

Mr Joko said Japan's foreign and defence ministers will meet their Indonesian counterparts this year to build cooperation in areas like security and counter-terrorism.

"Amid the spread of terrorism ideology, Japan will cooperate with Indonesia, which has a moderate Muslim population," said Mr Abe. "Our aim is to produce a young generation who have hope."

Mr Joko described the meetings with Mr Abe as "warm, open and productive".

"In the midst of a global economy that has not rebounded, Indonesia still recorded a very significant increase in investment from Japan," he said, adding that the US$4.5 billion (S$6.4 billion) worth of Japanese investments in his country in the first nine months of last year was almost double that registered over the same period in 2015.

Mr Abe will leave Indonesia for Hanoi today. He is due to meet his Vietnamese counterpart, Mr Nguyen Xuan Phuc, as well as President Tran Dai Quang.