The government has pledged £4.85m to help local firms develop the businesses case for a Crossrail extension to Ebbsfleet in Kent.
The delayed £17.6bn Elizabeth Line will stretch from Abbey Wood in the east to Heathrow in the west when it is due to open around 2020.
A number of MPs and local businesses, including the Thames Estuary Commission, London City Airport, the London Chamber of Commerce and HS1 – also known as the Channel Tunnel – have all backed an extension from Abbey Wood to Ebbsfleet.
MPs including former defence secretary Michael Fallon, Labour MP Teresa Pearce and Tory MP David Evennett believe the extension into Kent, which was included in the original design but removed in 2008, should be restored following the economic rebuilding from the financial crash.
London City Airport has long campaigned for a Crossrail station at the airport, where it could absorb some of the passengers that use the Royal Docks terminal.
In a written ministerial statement, housing secretary James Brokenshire confirmed the government's support for the Thames Estuary Commission's pitch that the extension would support £1.3m new jobs, a £190bn boost for the economy and 1m new homes.
Crossrail bosses are due to give an estimate for when the railway could open around April.
Crossrail's chief executive Mark Wild has so far refused to confirm any date for when the railway will open, but has said the company "very, very much wants to get this done in 2020".