Prime Minister Shinzo Abe on Tuesday declared that Japan would not take part in multilateral combat operations such as the 1990-1991 Gulf War or the US-led 2003 war in Iraq.

He was speaking at a news conference after his cabinet adopted a resolution to lift a ban that has kept the military from fighting abroad since World War Two.

Japan took the historic step away from its post-war pacifism on Tuesday by ending a ban that has kept the military from fighting abroad since 1945, a victory for Prime Minister Shinzo Abe but a move that has riled China and worries many Japanese voters.

The change, the most dramatic policy shift since Japan set up its post-war armed forces 60 years ago, will widen Japan's military options by ending the ban on exercising "collective self-defence", or aiding a friendly country under attack.

Abe's cabinet adopted a resolution outlining the shift, which also relaxes limits on activities in UN-led peace-keeping operations and "grey zone" incidents short of full-scale war, Defence Minister Itsunori Onodera told reporters.

Long constrained by the post-war constitution, Japan's armed forces will become more aligned with the militaries of other advanced nations in terms of its options. However, Tokyo will be wary of putting boots on the ground in multilateral operations such as the 2003 US-led invasion of Iraq.

Abe repeated that stance on Tuesday, while stressing Japan had to respond to an increasingly tough security environment.

"There is no change in the general principle that we cannot send troops overseas," Abe told a televised news conference, flanked by a poster showing Japanese mothers and infants fleeing a theoretical combat zone on a US vessel under attack.

The US, which defeated Japan in World War Two then became its close ally with a security co-operation treaty, welcomed the Japanese move and said it would make the US-Japan alliance more effective.

"This decision is an important step for Japan as it seeks to make a greater contribution to regional and global peace and security," Defense Secretary Chuck Hagel said in a statement.

"The US has an enduring interest in the Asia-Pacific's peace and prosperity, and our alliance with Japan is critical to our strategy in the region," Hagel said.

Hagel added that he looked forward to discussing Japan's decision when Onodera visits Washington next week.

Washington has long urged Tokyo to become a more equal alliance partner and Japan's move will also be welcomed by Southeast Asia nations that like Tokyo have territorial rows with an increasingly assertive China.

Tokyo's new policy has angered China, whose ties with Japan have frayed due to a maritime row, mistrust and the legacy of past Japanese military aggression.

"China opposes the Japanese fabricating the China threat to promote its domestic political agenda," Chinese Foreign Ministry spokesman Hong Lei told a news conference in Beijing.

"We demand that Japan respect the reasonable security concerns of its Asian neighbors and prudently handle the relevant matter," he added.-Reuters