
Prime Minister Yoshihiko Noda announced the commitment during a summit meeting with the premiers of Laos, Cambodia, Thailand, Vietnam and Myanmar.
Japan intends to boost its presence in the region to counter China's growing investment and influence.
"Development and progress of the Mekong region is the key to development and stability in East Asia," Noda said at the fourth annual meeting, Kyodo News reported.
Tokyo pledged the assistance with "expectation that this will be accompanied with the transmission of Japanese expertise," a joint statement said.//DPA