Tokyo: Prime Minister Yasuo Fukuda today told a resurgent opposition that Japan must not be a "bystander" in the US-led "war on terror" as he fought to extend a naval mission in the Indian Ocean.

The opposition won control of one house of parliament in July elections and has vowed to defeat government proposals to extend the naval mission providing fuel and logistical support to US-led forces in Afghanistan.

The opposition has so far ignored a government compromise that would stop refuelling operations backing combat troops, restricting support to ships policing the Indian Ocean.

Addressing a parliamentary committee attended by key lawmakers from the ruling coalition and opposition, Fukuda said that Japan, as the world's second largest economy, needed to contribute to international security.

Saying that the international community was united after the 2001 terrorist attacks on the United States, Fukuda said: "How can we sit back as a bystander?"

"We felt powerless at not being able to do anything when the international community took concerted action after Iraq invaded Kuwait in the Gulf War," Fukuda said.

In 1991, Japan faced heavy international criticism for not committing personnel to the first Gulf War, which it bankrolled to the tune of about $13.5 billion -- or 20 percent of the international contribution.

He also assured the opposition that the Indian Ocean mission does not violate Japan s pacifist constitution, which was imposed by the United States after World War II.

"First of all, the mission is not an act of force," Fukuda said. "It does not infringe on the constitution at all."