The extension will consist of new twin bore tunnels of 5.2m internal diameter running for 3.3km with new stations built at Battersea and Nine Elms.

London Underground said it aims to pre-qualify contractors and consortia able to deliver this complex project and bring innovative ideas to the table deliver significant cost, risk, programme savings.

In a OJEU procurement notice, the Tube operator said it would use a negotiated procedure to select the winning bidder. Interested firms have until 15 April to complete the prequals.

The design of the underground project has progressed to RIBA Stage C and the successful firm will be expected to work on the fine-tuning these plans.

A contract is due to be signed on 6 January 2014 with project completion scheduled for the end of 2019.

The proposed Northern Line extension is essential to support the transformation of Vauxhall and Nine Elms which will see up to 16,000 new homes built in the area over the next 20 years