TOKYO, Jan 21: Japan's opposition camp on Wednesday stepped up pressure on Prime Minister Junichiro Koizumi over the dispatch of troops to Iraq amid expectations that the formal order for a full deployment will come as early as Monday.

At the start of a three-day parliament session, Naoto Kan, head of the nation's largest opposition bloc, the Democratic Party of Japan, demanded Mr Koizumi's resignation, saying the planned deployment is unconstitutional.

"Sending the Self Defence-Forces (SDF) to a battlefield is like trampling down on the principle of the constitution," Mr Kan told parliament amid cheers and jeers.

"Prime Minister Koizumi, who gave an order for activities which contravene the current constitution, lacks the qualifications for prime minister," Mr Kan said.

Japan has already dispatched three advance teams to Kuwait and the southern Iraqi city of Samawa ahead of its planned deployment of the core contingent of troops, in the first deployment by Japan's military in a hostile region since World War II.

The country's post-war constitution bans the use of force in settling international disputes and the deployment plan has aroused fears among neighbouring nations about a militarist revival in the country.

Mr Koizumi defended his decision to send troops to Iraq, saying: "The SDF will carry out humanitarian assistance in non-combat areas. Legitimate self-defence is totally different from the use of force under a state order."

News reports said on Wednesday that Mr Koizumi plans to formally order the defence agency to send main units of the Ground Self-Defence Force (army) to Iraq as early as Monday.

Mr Koizumi will be briefed about security conditions in Samawa by some members of the advance team who will return to Japan on Friday, the Asahi Shimbun and Jiji Press said, quoting government sources.

Mr Koizumi would then give the green light for deployment after notifying his coalition ally, the New Komeito party. As a first step, 80 ground troops are to fly to Samawa by the end of the month to begin constructing a base camp, they said.

Japan is then to send some 440 personnel during the next month and March so that the troops can begin providing humanitarian and reconstruction support, including work on the water supply.

The Japanese air force is to send the first of the main contingent to the Gulf on Thursday. Some 150 air force personnel will leave their base in central Japan for Kuwait in order to join an advanced team to handle airlifts of such items as food, medicine and other goods between Kuwait and Iraq. -AFP