LONDON (AP) — U.K. Olympic organizers run a risk of exceeding their 9.3 billion-pound ($14.6 billion) budget for hosting the 2012 London games and have little room left for unforeseen costs, Britain’s spending watchdog warned Tuesday.

The National Audit Office report concluded that while the venues are on time and largely complete, “not everything is rosy.” The report came as British Olympic officials announced that they had doubled the funding for security operations at venues, raising overall security costs for the 2012 Games to more than 1 billion pounds ($1.6 billion).

“The government is confident that there is money available to meet known risks, but, in my view, the likelihood that the games can still be funded within the existing 9.3 billion-pound public sector funding package is so finely balanced that there is a real risk more money will be needed,” said Amyas Morse, the head of the National Audit Office.

If that’s the case, Olympic officials would be heading back hat in hand to British taxpapers who are already embroiled in tough economic times. The Organization for Economic Cooperation and Development expects the U.K. economy to contract in this current quarter and in the first three months of 2012 and grow only 0.5 percent next year.

Britain’s National Audit Office, an independent organization, examines public spending on behalf of Parliament.

Just hours before the report, Olympics minister Hugh Robertson told reporters at a news conference that the London Games remained financially on track — and within budget contingency planning despite the increased security costs. But the new security costs will certainly become a sensitive political issue.

“We’re confident we can do this and remain on budget,” Robertson said.

But the auditors noted that only 500 million pounds ($785 million) remains unallocated for dealing with future costs — a fact that will alarm ministers already trying to stem public anger over cuts in pensions, social services and national programs. Security and transport costs figured among the question marks in the future.

The increase comes after security reviews suggested the initial estimate of 10,000 security guards for the games would not be enough. Thousands of soldiers are now part of the planning, though officials have declined to reveal the exact number.

Robertson made clear that security was not a negotiable item and that the British government was obligated to make sure it took every precaution to make the July 27-Aug. 12 event safe.

The government said an additional 271 million pounds ($424 million) has been allocated to making venues and other sensitive sites, such as hotels, more secure. That means the total cost of securing the venues has climbed to over 553 million pounds ($862 million).