Budget airline Ryanair could allow passengers to fly for free, by reaping costs back from in-flight gambling systems.

Ryanair, the world's second largest international air carrier, has announced it hopes to launch an onboard gambling service within the next 12 to 18 months, provided it can develop a credit-card payment system which authorises passengers' bets instantly.

If the onboard gambling proves successful, seats would then be able to be given away free as the need to charge fares for travel would be compensated by the revenue from the gambling.

Passengers on Ryanair flights will be able to access the games via Blackberry-enabled mobile phones or devices issued by the airline.

However, Ryanair chief executive Michael O'Leary denied encouraging gambling in planes would ruin the reputation of the aviation industry.

"The flag carriers have been ripping us all off for the last 40 years