The agreements relate to the delivery of land, development rights and the provision of infrastructure, as well as utilities and services to Stratford City and the Olympic facilities.

The Australian company's plans for Stratford City, the urban regeneration site adjacent to the Olympic Park, were a key element of a briefing given to Prime Minister Gordon Brown today by Frank Lowy, the chairman of Westfield Group at 10 Downing Street.

Lowy said: “The £1.5 billion Stratford City retail and leisure development has both scale and significance, serving as a gateway to the Olympic Park and delivering real momentum to the regeneration of east London.

"We anticipate significant transformation flowing from the 2012 Olympics, with Stratford City becoming the metropolitan centre of East London.”

Gordon Brown said: "Development in and around the Olympic Park site will bring real benefits to the people of East London, transforming the local area and bringing billions of pounds of private investment into one of the most disadvantaged parts of the UK.

"Regeneration was at the heart of our bid for the 2012 Olympic and Paralympic Games, so I welcome the excellent progress being made on the Stratford City development."

Also present at the meeting were Boris Johnson, Mayor of London; Sir Robin Wales, Mayor of Newham; Tessa Jowell, the Olympics Minister; Sebastian Coe, the London 2012 chairman; John Armitt, chairman of the Olympic Delivery Authority (ODA); and David Higgins, chief executive of the ODA.

Johnson said: “The enduring benefit to London of the Olympic Games is the legacy they leave behind.

"Westfield’s investment is a significant step towards achieving that legacy and a major contribution by the private sector to creating new opportunities for people in East London.”

At the hub of two of the busiest underground lines, an expanded Docklands Light Railway network and the new international high speed rail link to continental Europe, and ultimately Crossrail, Stratford City will also benefit from a range of regional overland services, including the improved North London line, and a new bus interchange.

Coe said: “We have what could be termed the hat-trick of regeneration - the biggest event on the planet, a world leader in retail development and a dynamic world city that is leading the way in urban regeneration.

"This powerful combination will super-charge the regeneration and opportunities for the communities in this area, delivering in a few years what would otherwise have taken decades to achieve.

"We are creating an exciting new chapter in the history of East London.”

The new development will be include a 175,000 sq m retail and leisure destination, anchored by John Lewis, Waitrose and Marks & Spencer.

The development will also feature around 300 local, national and international fashion, home and lifestyle brands, as well as a variety of leisure and entertainment experiences and is due to open in 2011.

Higgins said: “This massive private sector investment is further evidence of how the Olympics are acting as the catalyst for the regeneration of East London.

"I have no doubt that Westfield has the vision, the values and the capacity to deliver a world-class retail, entertainment and leisure destination for the capital.

"We look forward to working in partnership with them.”