By Kanupriya Kapoor and Linda Sieg
JAKARTA/TOKYO (Reuters) - Indonesian President Joko Widodo said one of China's main claims to the majority of the South China Sea had no legal basis in international law, but Jakarta wanted to remain an "honest broker" in one of Asia's most thorny territorial disputes.
Widodo's comments in an interview with a major Japanese newspaper came as he embarked on a visit to Japan and China, and was the first time he had taken a position on the issue since coming to power in October.
China claims 90 percent of the South China Sea, which is believed to be rich in oil and gas. Brunei, Malaysia, the Philippines, Vietnam and Taiwan lay claim to parts of the sea, where about $5 trillion of ship-borne trade passes every year.
The territorial dispute is seen as one of Asia's hot spots, carrying risks that it could spiral out of control and result in conflict as countries aggressively stake their claims.
"We need peace and stability in the Asia-Pacific region. It is important to have political and security stability to build up our economic growth," Widodo was quoted as saying in an interview with the Yomiuri newspaper published on Monday.
"So we support the Code of Conduct (of the South China Sea) and also dialogue between China and Japan, China and ASEAN."
But in a Japanese version of the interview published on Sunday, Widodo rejected one of Beijing's main claims to the South China Sea.
"The 'nine-dashed line' that China says marks its maritime border has no basis in any international law," said Widodo.
Maritime lawyers note Beijing routinely outlines the scope of its claims with reference to the so-called nine-dashed line that takes in about 90 percent of the 3.5 million square kilometers South China Sea on Chinese maps.
The president was not speaking on China's overall claim on the South China Sea, but only its nine-dash dotted line that stretches deep into the maritime heart of Southeast Asia, his foreign policy adviser Rizal Sukma told Reuters on Monday.
"In 2009, Indonesia sent its official stance on the issue to the U.N. commission on the delimitation of the continental shelf, stating that the nine-dotted line has no basis in international law," said Sukma. "So, nothing changes."
China's Foreign Ministry appeared to downplay the remarks, repeating its standard line about Chinese sovereignty and that the dispute needs sorting out between the countries directly involved.
"The core of the South China Sea dispute is because of some countries' illegal occupation of several islands in the South China Sea and their adjacent waters has caused overlapping maritime claims," spokesman Hong Lei told a daily news briefing.
China recently expressed its anger at the Vietnamese head of the Association of Southeast Asian Nations (ASEAN) when he rejected Chinese claims based on the nine-dash line.
This vague boundary was first officially published on a map by China's Nationalist government in 1947 and has been included in subsequent maps issued under Communist rule.
Indonesia, the largest country in Southeast Asia, has been a self-appointed broker in the myriad territorial disputes between its neighbors and China over the South China Sea. "Indonesia's willingness as an honest broker remains the same," Sukma said.
In his first trip to Japan as president, Widodo met Prime Minister Shinzo Abe on Monday and their defense ministers signed a defense pact to promote dialogue and cooperation.
The agreement is the latest effort by Tokyo to forge closer security ties with Southeast Asian nations and build a counter-balance to China.
Besides the defense pact, Japan agreed with Indonesia to strengthen cooperation in maritime security and development of marine-related industries. Japan also announced 140 billion yen ($1.17 billion) in official development assistance to help build Indonesia's railway network.
Japan has already bolstered partnerships with the Philippines and Vietnam, the two countries most at odds with China over the South China Sea. Japan itself is embroiled in a bitter dispute with China over uninhabited islands in the East China Sea, further to the north.
Widodo will visit China after Japan. Indonesia and China have a more developed military relationship and Jakarta has bought Chinese-made missiles and other military hardware.
(Additional reporting by Sui-lee Wee in BEIJING, Kiyoshi Takenaka in TOKYO; Editing by Michael Perry and Simon Cameron-Moore)