LOS ANGELES, Jan 25: The Bush administration’s commitment to help cover Pakistan’s military costs in support of US forces in Afghanistan is far larger than previously disclosed, totalling hundreds of millions of dollars in still-unpaid bills.

The Pentagon estimates the tab totals nearly $350m to $100m a month — and how it will be met is still unclear, reports Wall Street Journal on Thursday.

The administration has been struggling to find a way to make the money available and win the approval of Congress, which has been kept largely in the dark about the costs.

“This is not a disagreement between the US and Pakistan,” a senior White House official said. A top defence official said: “We need to strike a balance between helping them out and reimbursing every cent they incurred.”

In the wake of the Sept 11 terrorist attacks, administration officials confirm that Secretary of State Colin Powell and Defence Secretary Donald Rumsfeld made oral commitments that the US would help the Pakistani military defray these operations.

Arizona representative Jim Kolbe, the Republican chairman of the House Appropriations panel, responsible for the annual foreign-aid budget, said he first became aware of the costs when the US ambassador to Pakistan, Wendy Chamberlin, raised the issue with him during a recent meeting in Islamabad.

Sen Daniel Inouye, a Democrat from Hawaii and chairman of the Senate Appropriations panel responsible for the Pentagon budget, said no one in the administration has yet told him of such costs, running at a monthly rate of about $100 million.

An initial payment of $100 million was approved by lawmakers late in final negotiations last month over the Pentagon budget.

Even then, that funding was intended to cover the cost of logistical and military support provided not only by Pakistan but also by Jordan. Mr Inouye said there was no warning that so much more money would be needed. “That’s not the understanding I got,” the senator said.

One reason for the confusion may be that the administration is still sorting out what is owed. Dov Zakheim, the Defence Department’s comptroller, recently travelled to Pakistan to review the situation, and the US hopes the government of President Pervez Musharraf will sign a more formal “cross servicing” agreement that will better spell out the cost-sharing arrangement.

That still leaves open the issue of how to pay for the bills already piled up, and the Pentagon may need new authority from Congress in order to cover what is more a payment-for-services-rendered relationship and not foreign aid.

An administration official said the language approved in the year-end deal last month is an important precedent. President Bush is expected to seek a new $10bn contingency fund for the military on top of a $38bn increase in defence spending for the new fiscal year that will begin on Oct 1.

But given the concerns in Islamabad, the unpaid bills will have to be addressed sooner and will almost certainly figure in debate this spring over supplemental spending for the military.