BAA, the airport operator, has misled millions of passengers about prices at shops and bars in its terminals, according to the advertising watchdog.

It has been forced to withdraw leaflets claiming that passengers are paying the same prices as in their local high street.

The Advertising Standards Authority upheld a complaint against the leaflets after finding that prices at airports were substantially higher. It found that passengers paid the same as at outlets in the City of London and the West End, where rents mean retail prices are the highest in the country.

A glass of house wine at a bar at Heathrow, Gatwick or Stansted cost 40 per cent more than in bars run by the same company in regional towns and cities. BAA makes almost half its revenue from retailing and has frequently been accused of focusing so heavily on maximising income from shops that it neglects airport facilities and fails to tackle the causes of delays.

One BAA leaflet, entitled Guide to Stansted Airport, stated: “The price of all food and drink sold in BAA airports is matched with the UK high street, so you won’t pay a penny more than you’ re used to.”

The leaflet listed airport food and drink outlets. A second leaflet, entitled Taste, stated: “Don’t forget, our caterers are committed to matching the price of all the food and drink they sell within their airport stores against their high street equivalents.” BAA told the ASA that it had contracts with retailers which demanded price parity with the high street. It claimed that prices at each airport were compared with the local high street, or, in cases where the retailer did not have a branch on that high street, with the nearest outlet.

BAA also claimed it carried out spot checks on all retailers to ensure their pricing matched the terms of the contract. But the ASA found that some retailers, in particular W H Smith and J D Wetherspoon, charged central London prices at the airports. W H Smith stores in Gatwick, Heathrow and Stansted airports matched their prices with five W H Smith branches in Central London: Holborn, Leadenhall, Oxford Street Plaza, Fleet Street and Baker Street.

J D Wetherspoon pubs at the three airports matched the average price charged at three of their premises in the City of London.

In its ruling, the authority said: “We considered that customers would see the claims ‘matched with the UK high street, so you won’t pay a penny more than you’re used to’ and ‘committed to matching . . . their high street equivalents’ as a reference to prices on their local high street or high streets near to the airports. We concluded the claims were misleading.”

A BAA spokesman admitted that “confusion may have been caused” by the leaflets. He said that the offending leaflets had been withdrawn and that the company would be taking action to ensure future communications with passengers about prices were clearer. He said it was “too early to say” if prices would be reduced.