The London 2012 Olympics and Paralympics are on track to be delivered under their $14.5 billion budget, with $740 million left in contingency funds, the British government said on Wednesday.

A budget of $14.5 billion was set in 2007 for the construction and delivery of the Games - almost four times higher than the original cost estimates presented at the time of London's bid in 2005.

Culture, Media and Sport Minister Jeremy Hunt, whose role includes responsibility for this year's Olympics, said it was "fantastic news" that, with 44 days to go to the Games, uncommitted funds remain available.

"Britain has proved that not only can we put on a great show for the world to watch like we did with the Jubilee but that we can also deliver big construction projects on time and on budget," he said, referring to the four-day celebrations for Queen Elizabeth II's Diamond Jubilee.

Total transformation

The Olympic Park project, involving more than 46,000 workers, has seen the transformation of a contaminated former industrial site into a 2.5 square kilometre site containing six new sporting venues. Some 75 per cent of investment in the Games has gone on the regeneration of East London, one of the poorer areas of the capital, according to the government.

More than 2,000 apartments in the Olympic Village, which will house 23,000 athletes and officials during the Games, will be converted into new homes after the event.

The ODA, which is responsible for building Olympic venues and related infrastructure, says its work is 98-per cent complete.

Olympics Minister Hugh Robertson said the Olympic Park was "the biggest construction project undertaken anywhere in Europe" and hailed it as a "blue print" for economic recovery in Britain.

He said all that remained to be done was "testing and refining".

In addition to spending on the park itself, some $10 billion has been invested in upgrades to public transport, he added.

Ministers played down fears that London could grind to a halt under the influx of visitors this summer and said 700 extra staff would be employed at London's Heathrow airport and other points of entry to Britain.

"We are as confident as we possibly can be that the transport system will hold," Robertson said.

The figures were announced as the Olympic torch continues its journey around Britain after being flown in from Greece on May 18. It will arrive at the Olympic Stadium in east London for the opening ceremony on July 27.