Olympic budget warning

There's a warning the £9.3b pound budget for the Olympics might not be enough and Londoners could be asked for more cash.

New stats from the National Audit Office suggest there could be trouble ahead now the cost of security has doubled.

Later the biggest dummy run of the 2012 games so far gets underway.

Three thousand staff will see how extreme weather, transport problems and security issues can be ironed out before next summer.