TOKYO (AFP) - Thousands of people are set to rally on Tuesday against government plans to soften Japan's commitment to pacifism and give its military a more active role, as a poll showed opposition to the moves.

Nobel Literature laureate Kenzaburo Oe will be among the speakers at the demonstration at a park in central Tokyo, organisers said. They estimated the event would attract several thousand attendees.

The protest is taking place after a national opinion poll showed there was growing public opposition to Prime Minister Shinzo Abe's push to bolster his nation's military.

He has argued that Japan needs to reinterpret its pacifist constitution to permit "collective defence" - coming to the aid of an ally under attack.

That is presently not allowed under current readings of Article 9 of the US-imposed document, which says Japan forever renounces the use of force as a means to settle international disputes.

Previous governments have held that this means Japan's military may only open fire if fired upon, even if that entails leaving US counterparts in danger on the same battlefield.

The liberal Asahi Shimbun reported that a poll of more than 2,000 adults nationwide showed 63 per cent of them are against the use of collective defence.

That was up from 56 per cent last year and more than double the 29 per cent who support the idea.

The percentage of those against revising Article 9 rose to 64 per cent from 52 per cent, the paper said in the poll published Monday.

Abe's drive to beef up the military provokes disquiet in China and on the Korean peninsula, where memories linger of Tokyo's brutal expansionism last century.

However, his position is welcomed in Washington, where there have long been calls for Japan to pull more of its own weight in a very one-sided security alliance.

Unease in Japan about China's increasing assertiveness, and specifically its strident claims to disputed islands in the East China Sea, has helped bolster Abe's push to enhance the role of the military.