Japanese Prime Minister Junichiro Koizumi announced his plan Tuesday to withdraw troops from Iraq at a ruling party meeting, an official said, moving to end Japan's largest military mission since World War II.

The official, who spoke on condition of anonymity because of party protocol, said Koizumi told a meeting of the Liberal Democratic Party that he would make a public announcement of the pullout later in the day.

Japanese Prime Minister Junichiro Koizumi arrives at the prime minister's official residence in Tokyo, Tuesday morning, June 20, 2006. [AP]

"We've finished this chapter," Kyodo News agency quoted Koizumi as telling party executives.

Japan has about 600 troops in the city of Samawah in southern Iraq. Although the mission is strictly non-combat and humanitarian, the deployment broke new ground as a symbol of Tokyo's more assertive military policy of recent years.

The move was prompted by the announcement on Monday that Britain and Australia would hand over responsibility for security to Iraqi forces in Iraq's southern Muthana province, where the Japanese troops are based.

Concerns have been high in Japan that the troops could be drawn into the fighting in Iraq, and the shift in security responsibility was apparently being taken as a chance by Tokyo to withdraw.

All major Japanese newspapers reported Tuesday morning that Koizumi would announce Japan's troop withdrawal after meeting with ruling and opposition party leaders to obtain consent, followed by a final decision by the government's national security meeting.

Defense Chief Fukushiro Nukaga will then issue an order for the withdrawal to begin later Tuesday, for a planned completion by the end of July, the Yomiuri newspaper reported.

Koizumi said in a televised news conference Monday that he wanted the withdrawal to be smooth and coordinated with Iraqi authorities. He also said Japan would continue to provide support for Iraq after the withdrawal.

The military mission has had only tepid support among the Japanese public, which has voiced concern about the safety of troops in Iraq and the possibility that the dispatch would make Japan a target of terrorists.

Foreign Minister Taro Aso, Chief Cabinet Secretary Shinzo Abe and Nukaga also met Monday to discuss the withdrawal and agreed to begin moving Japanese troops out after Iraqi authorities move toward taking over responsibility for security in the area from British forces, Nukaga said.