It once threatened to make its passengers pay to use the toilets on board its aircraft.

Now Ryanair has come up with another creative way of making more money: by allowing other companies to advertise on its planes – for a price.

The low cost airline is selling what it claims is the “largest and cheapest” form of outdoor advertising in Europe by offering for its 300-plus aircraft to be painted with the branding of another company.

Planes will continue to have Ryanair’s logo on the tail fin but companies can buy advertising on other parts of its aircraft, including the tips of the wings and the main body of the plane.

The self-styled “ultra low cost carrier” wouldn’t reveal the name of the first company that will take up the offer but a spokesman said the idea had already generated a lot of interest.

“It’s certainly proving popular,” he said, adding that it was “very cheap”.

Ryanair, which started in 1985 with a staff of just 25 people, has carried advertising on the outside of its aircraft before.

Last decade it experimented with repainting its planes in their entirety in another company’s branding, such as Jaguar or Guinness.

More recently, it has been testing advertising on some of its Spanish routes but has now decided to roll-out the scheme to all of its 303 aircraft. Companies can advertise on as little as one aircraft for 12 months.

Donal O’Neill, airlines analyst at Goodbody, said he didn’t expect the revenues to be “huge” but it would be another cash generator for Ryanair, which is well practiced at making money out of added extras – or “ancillary revenues” – such food, drink and baggage charges.

“We wouldn’t expect the revenue from this to be huge, but it’s another increment on the bottom line,” Mr O’Neill said.

In the year to March 31, Ryanair’s ancillary revenues climbed to €1.1bn (947m), a fifth of its total operating revenues.

Photo Credit: Ryanair planes are seen parked at Girona airport. Albert Gea / Reuters