Washington: US Senators have said that they have taken a major step to halt a controversial military base plan on Japan's Okinawa Island and called on the Pentagon to make a fresh assessment.

Brushing aside insistence by the two governments that plans should go ahead, the Senate Armed Services Committee agreed to bar any funds to move troops from Japan to Guam and ordered a new study on Okinawa's flashpoint Futenma base.

The language was part of an annual defense funding act approved on Thursday. It needs approval from the full Senate and House of Representatives, but senators involved said that their actions on Asian bases enjoyed broad support.

Senator Carl Levin, a member of President Barack Obama's Democratic Party who heads the committee, said that the base plan in Japan increasingly appeared unfeasible and that the United States needed to control costs.

"This is a major step to put all these changes on hold and to require some analysis of cost and to take an honest look at what the current plans are and what the alternatives are," Levin told reporters on a conference call on Friday.

The Senate intervened even though the Obama administration had put its foot down with Japan, insisting that the base plan could not be changed. One Japanese Prime Minister, Yukio Hatoyama, resigned last year after failing to fulfill campaign promises to come up with a new plan on the Futenma base.

"I think people have kind of hidden their heads in the sand because everyone just says, 'We've got a plan, we're going to keep going.' But the problem is the current plan isn't affordable, it's not workable," Levin said.