Japan's cabinet on Thursday approved a set of bills bolstering the role and scope of the military, as the pacifist country redefines its position in the increasingly roiled Asia-Pacific region.

The bills are a pet project of nationalist Prime Minister Shinzo Abe, who says Japan can no longer shy away from its responsibility to help safeguard regional stability, and must step out from under the shade of the security umbrella provided by the United States.

The draft legislation, which will go before lawmakers in the coming months, formalises a decision made by the cabinet last year to broaden the remit of Japan's well-equipped and well-trained armed forces.

It would allow them to go into battle to protect allies -- so-called "collective defence" -- something currently banned by a strict reading of Japan's pacifist constitution.

"We live in an era when no country can any longer protect itself alone," Abe told a televised press conference.

"In the past two years, Japanese nationals have fallen victim to terrorism in Algeria, Syria and Tunisia; Japan is within range of hundreds of North Korea's ballistic missiles and the number of (fighter jet) scrambles has risen seven-fold in a decade.

"This is the reality. We should not try to ignore it."

Washington -- which imposed the never-altered constitution on a defeated Japan during its post-World War II occupation -- has long called for Tokyo to take on a more active role in their mutual security pact.

- Opposition -

But the Japanese public is suspicious of anything that seems to lessen the commitment to pacificism, and insists its armed forces should only ever be used in a narrowly-defined defence of Japan.

Critics of the security moves say eroding this principle could see Tokyo pulled into American military adventures in the Middle East, a claim Abe rejected Thursday.

"The conventional principle that (the military) shall not be deployed overseas will stay. They will not take part in conflicts like the Gulf War or Iraq War in the future. I want to make that clear," he said.

He said the last 70 years had proved that Japan was committed to peace and the country should be confident in its ability to stick to that path, without fearing these legal changes would drag it into conflict.

"Not a single Japanese person wants to see a war," he said.

Hundreds of people rallied in front of Abe's office Thursday, holding banners condemning the proposed legal changes.

"The bills will eventually serve as a green light to join an American war. It is clearly a violation of the constitution," said 66-year-old Akemi Kitajima.

Abe also faces Chinese charges that he is re-militarising Japan by stealth in an effort to return to its warring ways of the 20th century. The prime minister and his supporters deny this.

In Beijing, foreign ministry spokeswoman Hua Chunying said the world was watching Tokyo for "historical reasons".

"We hope that Japan will draw lessons from history, pursue the path of peaceful development, and make more positive efforts for the peace, stability and development of the Asia-Pacific region where we live together," she said.

The legislation, which would overhaul 10 security related laws and create a new one, would pave the way for the military to deploy abroad on non-combat assignments such as disaster relief and UN peacekeeping missions.

Revisions include removing geographical constraints on logistical support for friendly forces in "situations that would significantly affect Japan's security".

They also say Japan can defend allies "in situations where there is a clear risk that Japan's existence is threatened and its people's rights...are compromised through an attack on a country which has a close relationship with Japan".

The cabinet decision comes as Japan hosts its first ever global arms fair, the result of relaxation in rules banning the sale of weapons abroad, as part of a bid to shore up the domestic arms industry.