Japan's Prime Minister Fumio Kishida instructed ministers on Monday to boost the country's defence budget by 56 percent over the next five years to US$318 billion.

Defence Minister Yasukazu Hamada said Kishida told him that "the size of the medium-term defence programme for the next five years, which is currently being arranged, should be around 43 trillion yen (US$318 billion)".

"This is a level at which we can achieve the goal of strengthening our defence capability," Hamada told reporters after talks with Kishida and the finance minister.

The amount would be more than 1.5 times larger than the current five-year spending plan of 27.5 trillion yen.

The decision comes a week after Kishida announced he wanted to increase defence spending to two percent of GDP by 2027.

For decades, Japan has spent around one percent of GDP or less on defence, less than the Nato standard of two percent. (AFP)