TOKYO, Nov. 8 (AFP) – The leaders of Japan and Southeast Asia's five Mekong River nations wrapped up a summit Saturday at which Tokyo pledged more than $5.5 billion in loans and grants and vowed deeper ties.

Prime Minister Yukio Hatoyama told a press conference the Mekong region was a ''priority area'' for Japan's official development assistance (ODA) as it seeks to boost development in the resource-rich area.

A joint declaration said ''Japan commits more than 500 billion yen of ODA in the next three years'' for the further development of the Mekong region, which includes Cambodia, Laos, Vietnam, Myanmar and Thailand.

''We strongly recognized the need for further strengthening of the Mekong-Japan relationship and cooperation to maximize the potential of the Mekong region,'' the statement said.

Asian giants Japan and China have for years poured aid and investment into the region, home to more than 220 million people, and are seen increasingly as competitors for influence.

Much of the region along the lower reaches of the 4,800-kilometre (2,980-mile) Mekong River has historically been isolated by war and political turmoil and remains poorer than other parts of Southeast Asia.

Hatoyama, who has pushed the concept of an EU-style Asian community, has set his sights on boosting economic development and has vowed to expand aid, particularly to Cambodia, Laos and Vietnam.

Eighty percent of the 5.5-billion-dollar package would be in low-interest yen loans, for projects ranging from regional highway links to water infrastructure and technological training, a government official said.

The leaders also agreed on an action plan to promote development, protect the environment and fight climate change under the slogan ''A decade towards the Green Mekong.''

And they demanded that Myanmar take steps towards democracy, calling for transparent elections next year.