WASHINGTON — The Bush administration is spending about $7 billion a month to wage the war on terror, and costs could total $570 billion by the end of 2010, assuming troops are gradually brought home, a congressional report estimates.

The paper by the Congressional Research Service underscores how the price tag has been gradually rising for the war in Iraq. A year ago, the Pentagon was calculating its average monthly costs in that conflict at below $5 billion — an amount the research service says has now grown close to $6 billion.

Since the Sept. 11 attacks, the administration has allocated about $361 billion for military operations, reconstruction and other programs in Iraq and Afghanistan, including $50 billion for 2006 in legislation working its way through Congress, the Congressional Research Service report said. The service is one of Congress' investigative arms.

CRS also identified gaps in the Pentagon's accounting of war costs, including up to $14 billion in funds that may have been transferred from peacetime accounts. It recommended that Congress require more detailed reporting from the Defense Department on how the money is spent.

The CRS report said the latest average monthly cost for Iraq is $5.9 billion, or 19 percent higher than last year.

The average monthly cost for operations in Afghanistan is $1 billion, or 8 percent lower than last year, and the costs of securing U.S. military bases worldwide averages $170 million a month, which is 47 percent lower than last year.

In projecting costs out through 2010, CRS said it assumed U.S. troops would remain in the region but drop gradually throughout the period.

The research service said the Pentagon will have to either increase the size of the Army, shift people from other missions or further increase the pace of the troop rotations.

U.S. troop total

highest since January

WASHINGTON — The number of U.S. troops in Iraq has grown to 152,000 and probably will hold near that level at least through the Oct. 15 referendum on a draft constitution, a Pentagon official said yesterday.

The troop total is now at its highest since shortly after the January elections for an Iraqi National Assembly, when the U.S. military increased its troop levels from about 138,000 to 159,000, mostly by delaying the departure of some units that had been scheduled to leave while new units flowed into the country.

The No. 2 U.S. commander in Iraq, Army Lt. Gen. John Vines, told reporters at the Pentagon from Baghdad on Sept. 2 that "the number of 140,000 is probably about right" for U.S. troop strength for the referendum.

Army Gen. George Casey, the top commander in Iraq, told reporters at the Pentagon, "I only had to ask for an additional 2,000 coalition troops to protect the referendum and election process this year, [compared to]12,000 in January."

Asked why the current force size was increased in light of the comments made by Vines and Casey, chief Pentagon spokesman Lawrence Di Rita said, "It's something that we are able to do, and we are doing it. And I think people shouldn't be too anxious to say, 'Well, six weeks ago, he said this.' That was six weeks ago. We're now where we are."

Officials said the force increase was accomplished with the previously disclosed deployment of roughly 2,000 new troops, and then adjusting the arrival and departure of troops as part of the regular rotation of forces.