Ryanair chief executive Michael O'Leary said Wednesday that the budget airline will only refund up to the cost of tickets bought by thousands of customers later left stranded by a volcanic ash cloud.

O'Leary said the Irish carrier would not give full refunds for the cost of hotel and food incurred by stranded passengers, potentially setting up a clash with the EU Commission, which insists airlines honour compensation rules.

"Why exactly are the airlines expected to be reimbursing people's hotels, meals and everything else when the governments are the ones who made a balls of this?" O'Leary told RTE radio.

"This legislation is not designed to cover a period of seven or eight days when passengers who paid us a fare of 20 or 30 euros are sitting in hotels for seven or eight days with their families and trying to recover a cost of over 1,000 euros from us. We will not be meeting those bills."

Under European law, EU passengers have the right to full reimbursement of airline tickets, including taxes, or for the carrier to arrange alternative measures to get them to their destination.

If this latter approach is taken then hotel rooms and food have to be provided until those alternative arrangements take place.

O'Leary was "fairly sure" that Ireland's Commission for Aviation Regulation would take legal action against Ryanair.

But he added: "We will look forward to seeing them in court because frankly I think this is a great opportunity for airlines to expose this nonsense."

A separate statement from Ryanair that while it will consider all passenger requests for reimbursements of receipted requests, "any such reimbursements will be limited... to the original air fare paid by each passengers."

Ryanair, which carries an average of 220,000 passengers on flights across Europe each day, is running some flights from countries including Spain, Italy, France and Morocco Wednesday.

It hopes to operate all northern European flights as scheduled from Thursday, except flights between Ireland and Britain which will resume from Friday.