The anticipated cost went up by 7 million pounds ($11.5 million) to 7.241 billion ($11.956 billion) during the last quarter, an increase of less than 0.1 percent, the Department for Culture, Media and Sport said.
Among other things, the rise was due to predicted higher spending for upgrading local sports facilities for Olympic training venues and costs of the Olympic Village and land and infrastructure projects in Stratford in east London.
The government said no contingency funds were released to cover the increases because they are expected to be offset by savings in other areas.
"This report shows we are still on time and still on budget," Olympics Minister Tessa Jowell said in a statement.
The overall public sector budget for the Olympics remains at 9.325 billion pounds ($15.397 billion).
The government released 2 million pounds ($3.3 million) in contingency during the quarter, including for additional seating for disabled people at the aquatics center and to allow the option of buying rather than leasing training pools at Eton Manor.
Of the 2 billion pound ($3.3 billion) reserve fund, 702 million pounds ($1.1 billion) has been released so far because of the economic downturn, although the government expects to recoup about half that amount through the future sale of Olympic Village housing units.
Still remaining in the contingency is 1.27 billion pounds ($2.1 billion), and the government estimates that 683 million ($1.1 billion) of that amount will be required.
With less than 1,000 days to go until the opening ceremony in 2012, the external structure of the main 85,000-seat Olympic Stadium is complete, the roof has been lowered into place on the aquatics center, and work is well under way on the three other main Olympic Park venues - the velodrome, athletes' village and main media center.
"There is no cause for complacency," Olympic Delivery Authority chairman John Armitt said. "Next year is set to be our toughest yet as activity on site reaches a peak and it is essential we maintain our momentum."
The report was released two days before International Olympic Committee officials arrive for their latest check on London's progress.
