Prime Minister Shinzo Abe pledges stronger security role for Japan

Prime Minister Shinzo Abe has vowed to keep boosting Japan's security role, saying that the officially pacifist nation should no longer be a "weak link" in the world.

Visiting New York for the UN General Assembly, Abe signalled on Wednesday that he hoped to move ahead with "collective self-defence" that would allow Japan to assist its ally the United States.

He also suggested that it was ironic that it was he who was dubbed a militarist in light of China's ballooning military spending.

"Japan should not be the weak link in the regional and global security framework where the US plays a leading role," Abe said at the Hudson Institute on the eve of his appearance at the UN General Assembly.

"Japan is one of the world's most mature democracies. Thus, we must be a net contributor to the provision of the world's welfare and security," he said.

"And we will. Japan will contribute to the peace and stability of the region and the world even more proactively than before."

Japan's US-imposed post-second world war constitution stripped the nation of its right to wage war. Under the constitution's current interpretation, Tokyo cannot use force except in the narrowest definition of self-defence.

In a scenario cited by Abe that sounded like a potential North Korean rocket launch, Japan would not be able to assist US ships near its waters if the vessels - not Japan itself - came under attack.

Abe, a conservative who is in a stronger political position than any Japanese prime minister in nearly a decade, has long supported a more active security role.

But any moves to inch away from Japan's steadfast pacifism could irk a coalition partner and anger neighbours China and South Korea.

Abe defended himself with a biting reference to "an immediate neighbour" - clearly China - saying it had been increasing military spending by more than 10 per cent annually.

"My government has increased its defence budget only by 0.8 per cent," Abe said.

"So call me, if you want, a right-wing militarist," he said sarcastically.