Japan's refuelling mission has proved controversial at home

The move follows the government's failure to agree a deal with the opposition to extend the mission beyond the end of its mandate on 1 November.

However, the government of Prime Minister Yasuo Fukuda has said it would try to pass new legislation to allow a more limited mission.

Japan has refuelled coalition warships in the Indian Ocean since 2001.

"The government will make its utmost effort... to resume an important mission in the Indian Ocean," chief Cabinet spokesman Nobutaka Machimura said.

The US ambassador to Japan, Thomas Schieffer, said a permanent withdrawal would send a very bad message to the international community and terrorists.

Mr Fukuda is due to visit the US next month, his first overseas trip since taking office.

Failed talks

Mr Fukuda held talks on Tuesday with opposition Democratic Party leader Ichiro Ozawa, who said he could only back an extension to the mission if it was part of a United Nations operation.

The two men are due to meet again at the end of the week.

The ships involved - a destroyer and a refueller, with 340 troops - are to head for Japan later on Thursday. They last refuelled a ship on Monday.

Japan's mission has been dogged by allegations that Japan supplied far more fuel to US forces than officially recorded - encouraging speculation that Tokyo might have helped supply the US war in Iraq, not just its operations in Afghanistan.

Japan's constitution forbids it from fighting other nations, but the government has recently tried to revise it to allow for a more robust defence policy.

Afghan President Hamid Karzai was "very appreciative of Japan's assistance, both economically and indirectly, as in the support to refuelling", his spokesman said.

But the spokesman, Humayun Hamidzada, added that the extension of the refuelling mission was a bilateral issue between the US and Japan.