CHITOSE, Japan - The first batch of troops who form part of the main contingent of Japan's contribution to peace-keeping in Iraq left for the Persian Gulf last Tuesday, in a historic move condemned by critics as a violation of the country's pacifist constitution.

Nudged by its key ally, the US, to take a bigger role in global security, Japan plans to send about 1,000 military personnel to help rebuild Iraq after last year's war. It is the first deployment of Japanese troops to a war zone since World War II.

About 90 soldiers have left Chitose on Japan's northern island of Hokkaido for southeastern Iraq, where they will build a camp on the outskirts of the city of Samawa.

"As Japan's representatives, we will do our best for the people of Iraq, for the stability of the region and for the sake of Japan," said Colonel Yasushi Kiyota, who heads the unit.

"We shall overcome all obstacles no matter how difficult and all return safely," he said at a farewell ceremony as some members of the soldiers' families wiped away tears.

The rest of the main contingent of nearly 600 members of the Ground Self-Defence Force - as the Japanese Army is known - is expected to depart in three waves beginning later this month.

The deployment has divided public opinion and Prime Minister Junichiro Koizumi's government is bracing for the possibility of the first Japanese military casualties since World War II.

The troops, equipped with anti-tank rocket launchers and recoilless rifles, will only be allowed to fire in self defence. They have been told to give a verbal warning and fire shots in the air before engaging any advancing enemy.

While they have been on peacekeeping missions previously, Japanese troops have not fired in combat since their surrender in 1945. About 300 demonstrators chanted slogans in a candlelight protest outside the Defence Ministry last Tuesday.

"We want the government to persuade the United States to withdraw from Iraq immediately, and also to bring back its own troops," said organizer Shingo Fukuyama.

In line with Japan's pacifist constitution, a law enabling the deployment limits activities to "non-combat zones", and government leaders have stressed the troops are not going to war.

The government has, however, acknowledged the risks.

"An advance team has been preparing for the arrival and the security situation has not changed," Defence Minister Shigeru told a news conference.

"But conditions could change any second, so we would like always to strive to gather information carefully and accurately."

Arab suicide bombers blew themselves up at the offices of two Kurdish parties in northern Iraq last Sunday, killing at least 67 people in one of the worst attacks since the war ended.

As the soldiers prepared to depart, Japan's main opposition Democratic Party boycotted an Upper House budget panel for a second day to protest against the ruling coalition's handling of a vote approving the dispatch in the lower chamber last week.

Party lawmakers returned after the ruling coalition agreed to allow additional debate.

Late last Friday, the ruling bloc rammed the vote through a Lower House panel despite vociferous opposition and the full chamber endorsed the dispatch in the early hours of Saturday.

Three LDP heavyweights, including former Defence Minister Koichi Kato, abstained in protest against the dispatch, which the law says must be approved, albeit retroactively, by both chambers of parliament.

(Agencies via Xinhua)