Japan's ruling and opposition parties remained deadlocked in parliament early Thursday over proposed security bills as thousands took to the streets in protests against legislation that could see troops fight overseas for the first time in 70 years.

An estimated 13,000 people had gathered under drizzle outside parliament in Tokyo demanding the bills be scrapped, ahead of the scheduled committee vote -- the penultimate stage before the bills become law in the officially pacifist nation.

But the vote was repeatedly delayed late Wednesday after opposition lawmakers blocked doorways in parliament, despite efforts from Prime Minister Shinzo Abe to consolidate cross-party support for the controversial legislation.

The government was forced to reschedule the special committee vote to 9:00 am Thursday (0000 GMT), a parliament official told AFP, yet there was continuing uncertainty over whether the committee would resume as scheduled.

Wednesday's street protests were the latest in weeks of rallies that have attracted tens of thousands to oppose Abe's plans to expand the role of the military, a show of public anger on a scale rarely seen in Japan.

"Japan is now heading towards war, blindly following the United States. The bills are against the constitution," said 55-year-old Makiko Inui as she stood in the rain outside parliament.

"Prime Minister Abe is wrong in his way of trying to build peace. We must oust Abe or Japan could be destroyed."

Organisers said 35,000 people had turned out for the rally, although police said 13,000 had gathered.

Earlier in the day hundreds of people faced off from a line of police outside a hotel in Yokohama, a city south of Tokyo, where lawmakers were holding a public hearing on the bills.

Demonstrators later began blocking roads, chanting anti-war slogans and trying to stop lawmakers from driving away after the debate.

- 'I am angry' -

"I am angry," said 28-year-old Hironobu Saeki, a graduate student at Ritsumeikan University in Kyoto, outside parliament.

"The Abe government... is taking its people too lightly," he said.

Under the planned changes the military -- known as the Self-Defence Forces -- would have the option of going into battle to protect allies such as the United States even if there was no direct threat to Japan itself or its people.

Although the current post-war constitution, which bars troops from taking part in combat except in pure self-defence, was imposed by US occupiers, many Japanese feel strongly any change would alter the country's pacifist character.

There are growing signs the bills have taken a toll on Abe's once high popularity. Opinion polls show the vast majority of the public oppose them.

But despite the fierce opposition, the bills are expected to be approved by both the committee and Japan's upper house, where the ruling coalition has a majority large enough to push them through.

Opposition parties have made every effort to block the bills, including by physically trying to prevent committee members from entering the chamber for Wednesday's debate.

But they were still expected to become law on Thursday or Friday.

Many legal scholars have said the changes are unconstitutional, and critics worry they would drag Japan into American wars in far-flung parts of the globe.

Abe and his supporters say the bills are necessary to deal with a changing security environment marked by an increasingly assertive China and unpredictable North Korea.