The estimated costs for London 2012 continue to rise

Tony Blair said the Games would be the "greatest sporting event on earth" but insisted a tight budget was key to its success.

Mr Blair was responding to concerns raised by MPs during Prime Minister's Question Time.

It comes following media speculation that costs for the Games could reach as high as �10bn.

Rising costs

David Evennett, Conservative MP for Bexleyheath and Crayford asked the Prime Minister: "With the increasing cost of the Olympics, do you share the concern of London council tax payers, particularly pensioners, about the Olympic levy and these rising costs."

Mr Blair said the Olympic Delivery Authority will publish its budget "in the next few weeks".

"Obviously it's important that we keep the costs properly under control but I think the Olympics will do an immense amount for London, for the whole of the country.

"I think, whether people are youngsters or pensioners or whatever age and in whatever part of the country, we should be extremely thankful we got the Olympics, we should make the investment necessary and we should make sure it is, as we believe it will be, the greatest sporting event on Earth in 2012."