Japan's ruling party pushed contentious security bills through a legislative committee Thursday, catching the opposition by surprise and causing chaos in the chamber.

Opposition lawmakers surged toward the chairman's seat to protest the vote as ruling party legislators tried to protect him. One lawmaker repeatedly clambered on top of the scrum.

A senior opposition leader later said they would not accept the vote, which happened without them knowing.

If the vote stands, the legislation will go to the upper house of parliament for final approval.

The bills would increase the military's influence, a highly sensitive issue in a country where many take pride in the pacifist constitution.

Lawmakers crowd around Yoshitada Konoike, chairman of the upper house special committee on security, during a vote in parliament in Tokyo on Thursday. A panel in the upper house approved legislation for a security policy shift that would allow troops to fight abroad for the first time since the Second World War a ruling party lawmaker said. (Yuya Shino/Reuters)

The legislative standoff is the latest development in a yearslong national debate about the way Japan uses its military. It has been a central question for the country since its armed forces were defeated in World War II seven decades ago.

Before the vote, opposition lawmakers introduced a no-confidence motion against the committee chairman, who earlier had tried to force the meeting to start.

The motion was the latest delaying tactic by opposition lawmakers who are trying to scrap the ruling party bills, which would allow the military to defend Japan's allies even when the country isn't under attack, work more closely with the U.S. and other allies, and do more in international peacekeeping.

Opposition claims constitutional violation

Despite the delays, the bills are likely to be passed eventually because Prime Minister Shinzo Abe's ruling bloc has a majority in the upper house.

Abe says Japan needs the bills to bolster its defence amid China's growing assertiveness and to share global peacekeeping efforts. Opponents say the legislation violates Japan's war-renouncing constitution, while putting Japan at risk of being embroiled in U.S.-led wars.

The ruling party's hope that final approval by the full upper house would take place later Thursday appeared increasingly difficult as the opposition plans to propose a series of no-confidence votes against Abe's Cabinet and its key members — a process likely to take more than half a day — before a house vote can take place.

Those no-confidence motions, however, are purely symbolic and meant to be delaying tactics. They would have no impact on the stability of Abe's government.

As the drama was playing out in parliament, a few hundred protesters continued to rally outside the building under a steady rain, after a bigger demonstration by thousands the previous night.

The protesters shouted "Scrap the bills right now" and "No to war bills," while flashing placards with anti-Abe and anti-war messages.