Global oil prices hit a record high of $147 a barrel last July before falling to a low of $32.40 in December as the global recession deepened.
Oil prices currently stand at about $67 a barrel.
Mr O'Leary said the carrier expected to report profits of between 200m and 300m euros for its current financial year, as its continues to attract more passenger through cutting ticket prices.
"I think the reason we're growing so strongly is you know we're this year going to carry twice the total number of passengers as British Airways, business class is now officially dead," he told the BBC.
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