(CNN) -- Recriminations are emerging in the wake of the volcanic ash crisis with airlines expressing anger over passenger compensation rules and demanding financial help for losses caused by what they say was a needless ban on flights.
Michael O'Leary, chief executive of budget carrier Ryanair, has led criticism of European Union regulations that require operators to feed and accommodate stranded passengers, saying his airline has only agreed to pay under duress.
"The events of the last seven days, under which Europe's airlines were prevented from flying by the closure of European airspace highlight how absurd and discriminatory the EU261 regulations are towards Europe's airlines," O'Leary said in a statement.
Ryanair, which sells some flights for less than $10 but charges for extras including baggage, earlier said it would reimburse claims up to the cost of tickets, but later backed down saying it would meet "reasonable" expenses.
"While competitor ferry, coach and train operators are obliged to reimburse passengers reasonable expenses, this reimbursement is limited to the ticket price paid to those operators," O'Leary added.
"Yet the airlines are required by regulation to meet potentially unlimited expenses, in circumstances where there has been a catastrophic closure of European airspace over the past seven days, as EU Governments and Regulators wrongly applied a blanket ban on flights over European airspace."
His comments follow complaints by airlines and industry bodies that the six-day flight ban imposed by authorities due to ash from and Icelandic volcano, were unduly cautious.
The International Air Transport Authority, which says the ban cost the industry $1.7 billion in lost revenue, called on the European Union to ease the financial burden on airlines.
Giovanni Bisignani, IATA's Director General and CEO, said the volcano crisis was an "act of God" beyond the control of airlines, who are now being victimized by unfair compensation regulations.
"The regulations were never meant for such extra-ordinary situations. It is urgent that the European Commission finds a way to ease this unfair burden," Bisignani said in a statement.
British Transport Minister Andrew Adonis said European authorities were considering requests for financial assistance by airlines and defended the flight ban.
"It was not a mistake. The safety authorities have quite properly been making safety their paramount consideration," Adonis told CNN. "Unless we can guarantee the safety of the air traveling public, there will be no planes flying at all."
He added: "The European Commission and the European Union is looking at the financial issue in respect of airlines. They are making proposals next week and I will of course be looking at those proposals."
Adonis also urged passengers to pursue claims against airlines.
"Passengers have right if they are with EU carriers to be re-routed, which gives them a ticket home and and food and accommodation in the period that they were unable to travel. These rights are enshrined in EU regulations and passengers should exercise them," he said.