Passengers flying with budget airline Ryanair will have to pay more for checked-in luggage in the peak summer period, it was announced yesterday.

The Irish no-frills carrier will raise its per-bag fee from £15 to £20 for all bookings made after midnight tonight for travel in July and August.

The £15 fee for checked-in bags will be in operation again from September.

Ryanair's Stephen McNamara said: "We are determined to incentivise passengers to travel light this summer by increasing our checked-in baggage fees for the months of July and August only.

"Over 70 per cent of all Ryanair passengers will be unaffected by these changes because they travel with no checked-in bags."

Rochelle Turner, head of research for Which? Holiday magazine, said: "Ryanair might claim that they are incentivising people to travel light, but we think it is more a case of penalising those families who can only go away on holiday during this time.

"Has (Ryanair chief executive officer) Michael O'Leary ever tried taking a family of four on holiday without a suitcase or two?

"Flying with Ryanair is not always as cheap as it first appears and we would advise passengers to factor in these extra costs when choosing who to fly with this summer."