Quoted Australian company Multiplex is poised to become a key developer in Britain after agreeing this week to a £2.1bn takeover of property firm Chelsfield.

Multiplex, best known in the UK as the contractor on Wembley stadium in north-west London, has joined forces with Australian rival Westfield and billionaire investors the Reuben brothers to buy the firm.

Multiplex is an established developer in Australia and Asia. Part ownership of Chelsfield will give the company access to high profile retail and mixed-use schemes. It will also boost its presence as a contractor.

Multiplex has entered into a 50/50 joint venture with the Reubens brothers. Multiplex and the Reubens between them own 40% of the shares in the joint venture, which has made a cash offer for Chelsfield with Westfield. Shares in Multiplex and Westfield rose on Monday after the agreement was announced.

Once the sale is completed the Multiplex/Reuben brothers joint venture has agreed to carve up Chelsfield’s assets with Westfield.

Westfield is expected to take control of its biggest asset, Merry Hill shopping centre in Dudley, West Midlands, while Multiplex and the Reubens have secured a 50% interest in the £2bn White City shopping centre in west London. At 120,000 m2, it will be the UK’s largest. It is due for completion in 2008. Multiplex is contractor.

In terms of investment properties, Multiplex will gain a stake in six retail properties comprising around 185,000 m2. Multiplex and the Reubens will have a 50% stake in Chelsfield’s mixed-use schemes in Stratford, east London, and Paddington basin, west London.

The joint venture is taking on a 50% stake in Chelsfield’s troubled internet business, Global Switch.

Multiplex, the Reubens and Westfield have secured the backing of 65% of the shareholder of Chelsfield for the deal. These include the Halifax Bank of Scotland (13%), whose founder, Elliott Bernerd (11%), is set to make £65m from the sale.

Westfield had intended to make a separate independent bid but backed away from the idea when it realised that Multiplex and the Reuben brothers, which own significant stakes in it, were not expected to sell.

Simon and David Reuben are relatively little known in the UK but are significant players. They moved to the UK from Iraq in the 1950s and own more than 100 properties.