The BBC's Bob Sinkinson: "Eurostar say the ticket prices are market driven"

Passengers from London pay £129 for a leisure class return to Brussels or Paris, while people buying the same ticket in Brussels pay only £108. In Paris it costs £115.

Similarly, fares from the intermediate station of Lille in northern France to London were £5 cheaper when booked on the Continent. First class fares are the same everywhere.

Eurostar said it has followed the pricing policy of airlines, who offer cheaper fares to European customers.

"We are competing with airlines and that is what determines the cost. Prices are set according to the price of corresponding flights in the different cities we serve. It is entirely down to the market," said a Eurostar spokeswoman.

British Airways 'pricing fiasco'

Customers in Paris pay less for the same journey

Earlier in the week it was revealed that British Airways offered huge discounts to Continental customers to fly internationally through London.

Martin O'Neill, chairman of the Trade and Industry Select Committee, said the discounts were a "pricing fiasco" for British consumers and called on the government to investigate the practice.

"I think we have to look at whether or not British Airways are abusing their market strength in the UK and if they are, then the regulatory authorities ought to come in and require them to reduce their prices," he told the BBC Radio 4 Today Programme.