From the Observer:

“The cost of the 2012 London Olympic is soaring amid growing fears that the final bill will be far higher than the original estimates. The Observer has obtained a letter from a senior civil servant to London mayor Ken Livingstone in which £1 billion of government money is pledged that ministers had not previously revealed would be forthcoming. The letter appears to contradict the government’s insistence that 2012 would not involve any central funding and would be paid for entirely from lottery receipts and a levy on the capital’s council taxpayers.”