Sir Adrian Montague has made an approach to London & Continental Railways, the company behind the Channel Tunnel Rail Link and co-owner of Eurostar.
The City banker and Treasury adviser is leading a consortium backed by Goldman Sachs that is looking at LCR, which is close to completing the long-awaited high-speed link between St Pancras station in London and the Channel Tunnel.
News of the approach, which emerged yesterday in a written statement from the Transport Secretary Alistair Darling, could flush out other bidders for LCR such as the financier Guy Hands.
Several of LCR's shareholders, which include Bechtel of the US, National Express and the Swiss bank UBS, are believed to be keen to find a way out.
However, the Government, which took on responsibility for almost £4bn of London & Continental's debt, would have the final say in any sale.
Sir Adrian, who started his City career at the law firm Linklaters before moving to Kleinwort Benson, has been a key adviser to the Government on a number of public-private projects.
He helped Network Rail take over from the defunct Railtrack business and is still chairman of British Energy, the nuclear power group that the Government helped bail out. He was also chief executive of the Treasury's PFI Taskforce in late 1990s.