[FONT=Verdana]Demolition work for the main 2012 Olympic venues has been completed and building will begin within months.

[/FONT] [FONT=Verdana]The Olympic Delivery Authority said it had reached a milestone in the project by clearing the way for the "big five" builds.

[/FONT] [FONT=Verdana]ODA chairman John Armitt said: "With such a huge project it was essential we got a good start. We have done that and are exactly where we planned to be.

[/FONT] [FONT=Verdana]"Big challenges lie ahead but we have put in place strong foundations. In 2008 we will change gear as we enter the start of the 'Big Build' phase with construction beginning in earnest in the summer."

[/FONT] [FONT=Verdana]Mr Armitt said it was a "major milestone" to have made way in the 500-acre park for the five venues - the main stadium, aquatics center, velodrome, Olympic village and media center.

[/FONT] [FONT=Verdana]More than 150 buildings have been demolished so far including a fridge factory on the site of the Olympic village, the Marshgate Lane industrial estate where the stadium will be and the twin towers of the University of East London straddling the velodrome and Olympic village sites.

[/FONT] [FONT=Verdana]The few remaining buildings, including a bus depot, will be cleared within weeks. Decontamination of the key sites will be completed early next year to create a platform for the construction phase. The first work begins on the Olympic stadium in April with piling to create the foundations.

Construction on the velodrome will begin in early 2009.

[/FONT] [FONT=Verdana]The number of workers in the park is rising rapidly, with about 2,000 employed largely in earthworks.

[/FONT] [FONT=Verdana]Early next year, Games chiefs plan to award contracts to build the velodrome and the aquatics center and to develop the media center in Hackney Wick.

[/FONT] [FONT=Verdana]The ODA said it had recycled 97 per cent of the building materials from demolition at a cost of about