LONDON (Reuters) - Ryanair's chief executive said Europe's largest budget carrier might start charging passengers for using the toilet while flying, but his spokesman cautioned Michael O'Leary often just made things up at will.

"One thing we have looked at in the past and are looking at again is the possibility of maybe putting a coin slot on the toilet door so that people might actually have to spend a pound (US$1.43) to spend a penny in future," O'Leary told BBC television.

He said this would not inconvenience passengers traveling without cash. "I don't think there is anybody in history that has got on board a Ryanair aircraft with less than a pound."

A spokesman said the airline had considered the fee as a possible source of extra revenue since passengers had the option of not using the toilet on board, but added that "maybe O'Leary was just taking the p*ss this morning."

"Michael makes a lot of this stuff up as he goes along and while this has been discussed internally there are no immediate plans to introduce it," Stephen McNamara said in a statement.

O'Leary has a reputation as a cost-cutter, expanding Ryanair by offering low headline fares and charging extra for items such as additional luggage.

Last week, Ryanair announced it was to shut all check-in desks at airports and have passengers check in online instead.

"We're all about finding ways of raising discretionary revenue so we can keep lowering the cost of air travel," he said.

(Reporting by Tim Castle and Andras Gergely; Editing by Dan Lalor, John Stonestreet)