The Diet on Friday approved a plan to deploy the Self-Defense Forces, allowing Japan to lend logistic support to U.S.-led military operations in Afghanistan.

The SDF plan was approved at a plenary session of the House of Councilors with the support of the ruling parties -- the Liberal Democratic Party, New Komeito and the New Conservative Party -- and a majority of the Democratic Party of Japan, the main opposition force.

However, two DPJ members, including former TV celebrity Kyosen Ohashi, voted against the plan, while another five abstained from voting despite the party's decision to support it.

"Within four weeks of the party voting against an antiterrorism bill, there was not even 1 mm of progress on how to secure civilian control (of the SDF, as the DPJ insisted)," Ohashi told reporters. "The public will not understand why the party made a complete about-face."

Ohashi was referring to what he believes is an inconsistency in the party's position. In October, the DPJ voted against the antiterrorism bill before expressing support for the plan to use the SDF to combat terrorism.

The DPJ member's "revolt" followed an earlier incident on Tuesday, when more than 20 DPJ lawmakers in the Lower House opposed the plan, giving the impression that the party is deeply divided.

"Personally, I don't think I can be (in the same party) with them any more," said Yasutomo Suzuki, hinting that they should step down from the party.

Suzuki and other conservative DPJ members on Thursday urged DPJ President Yukio Hatoyama to severely punish those who opposed the SDF plan.

Meanwhile, Social Democratic Party leader Takako Doi said she will seek the cooperation of DPJ Vice President Takahiro Yokomichi, who voted against the plan Tuesday, to defend the Constitution.

The DPJ's leadership will decide on any punishments early next week.

SDF bill approved

The House of Representatives approved a bill Friday that allows the Self-Defense Forces an expanded role in U.N. peacekeeping operations and eases restrictions on firing weapons.

The bill would lift a ban on activities such as monitoring ceasefires, disarming local forces and patrolling demilitarized zones. The SDF is currently empowered to participate in humanitarian roles such as engineering and medical care.

The bill would also ease current rules so that SDF personnel can use their weapons not only to defend themselves but also to defend "those who fall under their control."

This would include refugees, U.N. workers and other nations' peacekeeping troops nearby.

The bill is expected to clear the Diet by Friday, the end of the current Diet session.