The Olympic Delivery Authority has admitted that there is a 20% chance it will use more than its original contingency budget to build the venues for the 2012 Games.

The ODA says there is an 80% chance that the programme can be delivered for £7.1bn. This includes the £6.1bn budget and the agreed contingency of £968m, but not the additional £1bn that the government is reserving to cover “unforeseen risk”. If all this was used it would bring the total cost to £8bn.

The revelation, contained in the body’s annual report this week, comes as it emerged that CLM, the delivery consortium that includes Mace, Laing O’Rourke and CH2M Hill, received £87.6m for its past year’s work.

Meanwhile, David Higgins, the ODA’s chief executive, will receive more than £500,000 for his work over the past year, including a £205,000 bonus. Howard Shiplee, the construction director, received £326,000, including a £52,000 bonus.

The ODA has so far spent £858m preparing for the Games. It said it had expected work worth £108m more to have been done by this date. It said the difference was owing to programme changes and cost savings on initial site works.