TOKYO (Bloomberg) — Secretary of State Hillary Clinton urged Japan and South Korea to cool tempers in their showdown over contested islands, as part of a wider U.S. effort to defuse rising regional tensions stoked by maritime disputes.

“I raised these issues with both of them,” Clinton said Sunday after meeting Japanese Prime Minister Yoshihiko Noda and South Korean President Lee Myung Bak at the Asia-Pacific Economic Cooperation Summit in Vladivostok, Russia. She said she told the countries’ leaders “that their interests really lie in making sure that they lower the temperature and work together in a concerted way to have a calm and restrained approach.”

Noda didn’t have bilateral meetings with the leaders of South Korea or China at the summit, only holding brief discussions with Lee and President Hu Jintao of China, with which Japan also has a dispute. A spokesman for the Chinese foreign ministry, Qin Gang, said Sept. 8 that Japan should “pay attention” to his country’s resolve to safeguard its sovereignty.

Clinton has tried to douse a diplomatic showdown between U.S. allies Japan and South Korea.

The escalating tensions, which come ahead of leadership changes in Japan, South Korea and China, have hurt Japanese companies such as Nissan Motor Co. doing business in China.

Noda tried to dial back tensions at the summit in Vladivostok, saying he had told Hu and Lee in their informal meetings that it was important to preserve and deepen ties. Noda said he also told Lee that ties between their countries were important because of the threat posed by North Korea.

“I said let’s build ties based on the big picture,” Noda told reporters.

The dispute with South Korea reignited after Lee made a surprise Aug. 10 visit to the islets, known as Dokdo in Korean and Takeshima in Japanese, which Noda called “unacceptable.”

China has condemned Japan’s plan to buy islands, known as Diaoyu in Chinese and Senkaku in Japanese, lying in the East China Sea near oil and gas reserves. Noda’s government is in talks to buy the islands from a private Japanese owner, a plan that was set off by an attempted purchase by Tokyo Governor and China critic Shintaro Ishihara.

The spat sparked anti-Japanese protests last month in China, which have affected deliveries for Nissan, Japan’s biggest automaker by sales in China. Nissan Chief Operating Officer Toshiyuki Shiga said Sept. 6 that the company had reduced the number of promotional activities on the advice of Chinese authorities in the wake of the demonstrations.

“Extending the hand of friendship and seeking to find common ground on these issues is a positive development,” Glenn Maguire, chief economist at consultant Asia Sentry Advisory in Sydney, said Sunday in e-mail. “With three separate territorial disputes, the risk for the Japan Prime Minister is that any concessions on these territorial disputes would reinforce perceptions of Japan’s declining influence in the region.”

Russian President Vladimir Putin, host of the APEC summit this year, said his country wants to resolve a territorial dispute with Japan over islands claimed by both nations. He and Noda agreed to have officials meet later this year to discuss rights to the islands.

APEC’s 21 economies have a market of almost 3 billion consumers, making up 44 percent of world trade and 56 percent of world economic output totaling $39 trillion in 2011, according to a fact sheet provided by the U.S. government. Leaders said Sunday in the summit communique that they were committed to take steps against protectionist trade policies.

“The territorial disputes will distract from APEC’s resolve to quickly usher in a free trade agreement for all of Asia,” Maguire said. “Such an outcome could leave the impression that Asia cannot work together when further strong multilateral gains on a range of issues need to still be made.”