BAA operates Glasgow and Edinburgh airports among others

EasyJet and Ryanair believe air travellers would get a better service if the airports owned by BAA, including Glasgow and Edinburgh, were forced to compete with one another.

The companies both told BBC Scotland that having one organisation manage the majority of airports was "bad business".

EasyJet in particular wants to see the two central belt airports competing against one another, a move which it said would drive down costs and increase standards.

Monopolies are bad for consumers, they result in less competition, higher prices and inferior service Michael O'Leary Ryanair

BAA, formerly known as the British Airports Authority, has dismissed the calls.

The company said it was proud of its record of investment in Scotland's airports and pointed to new research showing that its landing charges were already highly competitive.

But Ryanair chief executive Michael O'Leary insisted there was no alternative to competition.

"BAA has ultimately a quasi-monopoly over the airports in the UK," said Mr O'Leary.

"Monopolies are bad for consumers, they result in less competition, higher prices and inferior service."

If you want to fly to Glasgow, you're not going to fly to Edinburgh instead because its 50 pence less expensive Mike Toms BAA

Mike Toms, BAA's group planning and regulatory affairs director, defended his company and said its landing charges were about the lowest in western Europe.

He told the BBC's Radio Five Live: "The market for airports is not like the market for airlines. Each airport serves its own city and it is its own market.

"If you want to fly to Glasgow, you're not going to fly to Edinburgh instead because its 50 pence less expensive.