Hanoi: Japan's Prime Minister Shinzo Abe on Monday promised Vietnam six new patrol boats during a visit to the Southeast Asian country locked in a dispute with China over the busy South China Sea waterway.

Abe's stop in Vietnam completes a tour through an arc of a region where Japan stakes a leadership claim in the face of China's growing dominance and uncertainty over what policy change Donald Trump will bring as US president.

Military music band play before a welcoming ceremony for Japan's Prime Minister Shinzo Abe at the Presidential Palace in Hanoi. Credit:AP

"We will strongly support Vietnam's enhancing its maritime law enforcement capability," Abe said, while emphasising that the dispute over the South China Sea should be settled through talks and in accordance with international law.

China claims almost all the South China Sea, through which about $US5 trillion worth of seaborne trade passes every year. Vietnam and four other countries also have claims in the sea, believed to have rich deposits of oil and gas.