Fares could fall after the sale of the high-speed line through Kent, with Eurotunnel likely to be among the bidding companies.

Earlier this week, the Government told London and Continental Railways (LCR) to start the formal process to sell High Speed 1 (HS1) that will eventually open it to competition.

An industry insider said competition in other transport sectors had often led to lower fares. "The idea is to see higher volumes of traffic and if that leads to more competition, more customers and to fares coming down, that will be good all round," he said.

Transport Secretary Philip Hammond was at St Pancras International to launch a sale of the 68-mile line. It is expected to realise at least £1.5bn and the concession will last 30 years. Apart from international travel benefits, HS1 will play a vital role in transporting spectators to and from the London 2012 Olympic and Paralympic Games.

LCR spokesman Ben Ruse said: "When you've got competition, this will benefit the passengers. It's a very exciting time." It could lead to direct services between London and Kent to Amsterdam, Cologne, Frankfurt and other Continental destinations, he said.

Eurotunnel, operator of the Channel Tunnel, is teaming up with partners Goldman Sachs and M&G to consider a bid before the July 9 deadline. Both partners have a stake in Eurotunnel and operate infrastructure investment funds. A successful bid could lead to more jobs being created in the county. However, the Eurotunnel consortium would face competition from foreign rivals, with German railways Deutsche Bahn a fancied bidder.

John Keefe, head of communications for Eurotunnel, said: "A private owner of the link would certainly be looking to get the maximum benefit out of it for the people of Kent. The principal way to make money out of an asset like that is to see more trains running on it."

LCR also owns a 40 per cent stake in Eurostar and land at Stratford and Kings Cross. A decision is expected before the end of March.