The Lower House approved a bill Thursday that will enable the Self-Defense Forces to lend rear-area support to U.S.-led retaliatory strikes against the Sept. 11 attacks on the United States.

The bill cleared the chamber in the afternoon in a standing vote backed by the ruling coalition -- the Liberal Democratic Party, New Komeito and the New Conservative Party. Two other related bills also cleared the chamber. One will enable the SDF to guard its own bases and U.S. bases in Japan, and the other will allow the Japan Coast Guard to fire on suspicious vessels.

The three bills were immediately sent to the Upper House and are expected to clear the Diet by the end of the month.

The ruling coalition has enough seats in both chambers to enact the legislation without opposition support.

The government-sponsored bill allows the SDF to provide logistic and other noncombatant support to the U.S.-led forces, engage in search-and-rescue activities for military personnel and carry out humanitarian relief operations.

It will also ease current restrictions on the use of weapons by SDF personnel, allowing them to protect not only themselves, but also those "under their care," including refugees and wounded foreign service members.

The legislation was revised to oblige the government to seek Diet approval sometime in the 20 days after an SDF deployment.

The revision also bans the SDF from transporting weapons and ammunition on land.

The Democratic Party of Japan -- the largest opposition party -- proposed a revision earlier this week that would oblige the government to obtain Diet approval before dispatching the SDF. But Prime Minister Junichiro Koizumi rejected the proposal, turning the DPJ against the bill.

The DPJ's position on the bill, however, seemed to cause a rift in the party, which is composed of both left-leaning lawmakers and conservatives who differ on core policies, such as national security.

Although the DPJ forbade its members from voting for the bill, one DPJ member who opposed the party's decision left the plenary session during voting to show his support, while another member outwardly supported the government-sponsored bill.

Two prominent members of the LDP, meanwhile, also left the session before the vote, saying the voting method chosen for the bill was inappropriate.

Earlier in the day, a political tug of war ensued as the ruling coalition and the opposition parties clashed on how to vote on the bills.

Both sides initially agreed to put the bill to a standing vote, but the LDP's junior coalition partners -- New Komeito and the NCP -- argued that such important legislation should be voted on by open ballot to show the position taken by each Diet member. The two parties apparently hoped the DPJ would fall apart over the bill.

But with the DPJ insisting that the earlier agreement should not be overturned, the Lower House Steering Committee reaffirmed that the bill should be put to a standing vote.