Ryanair passengers must pay £20 to check in each bag this July and August on bookings made from midnight tonight.

The increase from the current £15-per-bag charge was announced at short notice and must be paid in advance online.

Ryanair said the increase was “avoidable” and presented it as an “incentive to passengers to travel light this summer”. But it is likely to generate £20 million for the carrier.

The increase means holidaymakers flying with Ryanair in peak summer will pay £40 return for each item of checked luggage, taking the typical bill for a family of four to £160.

The carrier permits just 10kg in carry-on baggage – nowhere near what most people take on a week’s holiday.

The check-in charge will return to £15 per bag from September 1.

Ryanair’s no-frills rival easyJet charges £18 return per checked bag.