Japan has announced it will ease its self-imposed arms export ban for the first time in almost 50 years.

The cabinet of Prime Minister Shinzo Abe has approved a new plan that replaces the 1967 blanket ban.

For decades the country has observed the "three principles" of not exporting arms to countries that are communist, subject to U-N arms embargos and involved or likely to be involved in international conflicts.

The new conditions will allow Japan to jointly develop arms with allies and give its defence industry access to new markets and technology.

"We have made the procedure for transfer of defence equipment more transparent," chief cabinet secretary Yoshihide Suga said.

"That will contribute to peace and international cooperation from the standpoint of proactive pacifism.

"And we will participate in joint development and production of defence equipment."

Japan's post-World War II constitution, imposed by the US-led occupiers, banned the country from waging war.

That pacifism was embraced by the population at large and two decades later a weapons export ban was introduced.

Supporters hope the relaxation in the policy will boost home-grown arms manufacturers at a time of simmering regional tensions including a territorial row with China and fears over an unpredictable North Korea.

The new rules could allow Tokyo to supply weaponry to countries that sit along important sea lanes to help them fight piracy - an important strategic consideration for resource-poor Japan.

Rising regional tension

Japanese arms could potentially be shipped to Indonesia as well as nations around the South China Sea such as the Philippines, which has a territorial dispute with Beijing.

Japan already supplies equipment to the Philippines' coastguard, an organisation that is increasingly on the front line in the row with Beijing.

Any move to bolster that support with more outright weapon supplies could irk China, which accuses Japan of increasing militarism.

Chinese foreign ministry spokesman Hong Lei says Beijing is paying close attention to the relaxation of Tokyo's arms ban.

"The policy changes of Japan in military and security areas concern the security environment and strategic stability of the whole region," he said.

"Due to historical reasons, Japan's security policies are always closely followed by regional countries and the international community."

China and Japan are at loggerheads over the ownership of a string of islands in the East China Sea, while Beijing is also in dispute with several nations over territory in the South China Sea, which it claims almost in its entirety.

AFP