The legal action filed with the Tokyo District Court seeks to block a decision by Prime Minister Shinzo Abe's cabinet last week to reinterpret rules which have long banned the use of armed force except in very narrowly-defined circumstances.

Tokinao Chindo, 75, a former civil servant in western Mie prefecture, said the move violated Japan's war-renouncing constitution, prompting his lawsuit, believed to be the first such action.

"I hope other Japanese people will follow suit and file legal actions nationwide," Chindo said.

Following the change, Japanese troops would now be able to come to the aid of allies -- primarily the United States -- if they come under attack from a common enemy, even if Japan is not the object of the attack.

The dramatic shift comes amid soaring regional tensions with China centred on disputed islands in both the South China and East China seas.

Beijing warned against the move, saying it opens the door to remilitarisation of a country that is not sufficiently penitent for its actions in World War II.

However, Australia and the United States, which has long encouraged Japan to take on more of a role in a very lopsided defence treaty, backed the decision.

The Philippines -- which was brutally invaded by Japan in World War II but is now engaged in a bitter territorial dispute with China over parts of the South China Sea -- also supported Tokyo's move.

- 'The Japanese shouldn't forget' -

Abe's move has caused anger at home, where the pacifism on which the constitution is built is an article of faith for many Japanese.

At least half the population opposes a more aggressive military stance, according to recent newspaper polls.

Following the historic decision, public support for Abe's cabinet slipped to below 50 percent for the first time since he swept to power in December 2012.

The conservative Abe had originally planned to change Article 9 of the US-imposed constitution, which was adopted after World War II and renounces "the threat or use of force as means of settling international disputes".

But unable to muster the two-thirds majority he needed in both houses and unlikely to get an endorsement from the public in the required referendum, he changed tack, opting to reinterpret the rules.

Chindo, who experienced World War II as a small child, told AFP: "I want to pass on the message 'never wage war' to the next generation."

"The Japanese shouldn't forget, just 69 years after the last war ended, that millions died during the war, and based on their sacrifices we embraced the Article 9" of the constitution, he added.

Building up military power would not work in safeguarding Japan but would only lead to an arms race, said Chindo.

"There are already a number of nuclear weapons that can destroy the Earth many times over," he said.

There was no immediate government reaction on the lawsuit, but Chief Cabinet Secretary Yoshihide Suga reiterated Friday the military shift was too small a step to require a revision to the constitution.

Speaking to reporters, he said "the constitution permits taking minimum necessary defence measures".

Elsewhere, Mitsushige Yamanaka, mayor of Matsuzaka city also in Mie prefecture, said this month he plans to launch a grass-route movement eyeing a similar lawsuit against the central government.