Channel Tunnel firm Eurostar is bidding to run a newly-privatised East Coast Main Line.
It will launch a joint bid with French company Keolis to operate the Edinburgh to London rail route.
The service has been run by the government since 2009, when National Express handed back the franchise mid-term.
Labour and trades unions have opposed returning the line to private control, arguing that it provides value for taxpayers.
The successful bidder is expected to be announced in October 2014, with the service running from February 2015.