(Adds details on spending, background, quotes)
By David Alexander
WASHINGTON, Aug 29 (Reuters) - U.S. military operations against Islamic State in Iraq have cost an average of $7.5 million per day since they began in mid-June, the Pentagon said on Friday, a figure that means the department has spent more than $500 million on the conflict.
Rear Admiral John Kirby, the Pentagon press secretary, told a briefing the expense of U.S. operations against Islamic State in Iraq had varied since U.S. forces became involved on June 16 but on average "it's costing us about $7.5 million per day."
"As our op (operational) tempo and as our activities have intensified, so, too, has the cost," Kirby said, noting that the figures were based on a snapshot of expenses between June 16 and Aug. 26.
He did not offer an estimate of the Pentagon's total costs so far, but an average cost of $7.5 million per day for 71 days would mean the department has spent roughly $532 million.
By comparison, the Pentagon has been spending roughly $1.3 billion per week on Afghanistan, analysts said.
The estimate includes like fuel for flying reconnaissance and strike missions, the cost of missiles and other weapons fired, as well as some payments for personnel, defense officials said.
The military so far has carried out 110 air strikes while flying about 60 reconnaissance aircraft sorties per day, defense officials said. In addition, it has sent more than 800 troops to evaluate the situation.
The operation is being paid for from the Pentagon's war-spending budget, which included some $80 billion in 2014, mainly for the conflict in Afghanistan.
"We're well within the limits that we need for 2014," Kirby said, noting that Defense Secretary Chuck Hagel has previously said the Pentagon would not require additional funds to cover the costs of Iraq this year.
But he said Hagel has noted the Pentagon might have asked Congress for more money in the 2015 fiscal year, which begins in October.
"Right now, in Iraq and elsewhere around the world, we've got resources sufficient to the military tasks that we're accomplishing," Kirby said.
"Once you get into '15, if we're still involved at this level or a higher level, then we've got to have another discussion about what the funding levels might be," he added.
He noted that the Pentagon was facing a larger budget problem in 2016 if automatic, across-the-board budget cuts return. The department is currently under orders to cut nearly $1 trillion in projected spending over a decade.
Congress agreed on a two-year deal for the 2014 and 2015 budgets that gave the department some relief from the financial uncertainty it has faced since being ordered to implement the cuts. But the automatic reductions are due to return in 2016.
The National Defense Panel, a group of former military and defense officials, warned in a recent report that the defense cuts ordered in 2011 constituted a "serious strategic misstep" that threatened to undermine U.S. security and global leadership. (Additional reporting by Missy Ryan; Editing by Eric Beech, Bernard Orr)