Media playback is unsupported on your device Media caption Ryanair boss Michael O'Leary: 'The demand for low fares is extraordinary'

Low-frills airline Ryanair has reported record profits as fare rises helped to offset a sharp rise in fuel costs.

Net profit for the year to March was 503m euros ($643m; £406m), up 25% on a year earlier. Revenue rose by 19% to 4.3bn euros.

The airline said traffic grew by 5% while fares rose by 16% on average, which helped to overcome a 30% rise in fuel costs.

However, it warned profits in the current financial year could be lower.

That warning hit the airline's shares, knocking as much as 7% off their value in early trading.

"Recession, austerity, currency concerns and lower fares at new and growing bases in Hungary, Poland, provincial UK and Spain will make it difficult to repeat this year's record results," the company said in a statement.

It forecast annual profits of between 400m euros and 440m euros for the year to the end of March 2013.

However, Ryanair chief executive Michael O'Leary told the BBC that his airline could benefit in some respects from the gloomy economic outlook.

"People don't stop going on holiday [altogether]. They just switch to lower cost carriers," he said.

He also rejected claims that Ryanair was not upfront enough in its charging structure.

"We don't have hidden charges, they are all out there [in the public domain]. We are the most upfront airline about charges," he said.

He said charges for checking in bags were there to change customer behaviour and make flying quicker for everyone.

'Cash cow'

The airline described its record profits for the last financial year as "commendable", particularly given the 360m euro increase in fuel costs. This was due to a 16% rise in the oil price, it said.

The company highlighted the fact that a number of European airlines had closed during the year, and said it had responded by opening a new base in Budapest and expanded bases in Spain, Scandinavia and the UK.

It also criticised the UK government's decision to raise air passenger duty, which it said had cut traffic by 6% since 2007.

"Many of Europe's governments continue to treat aviation (and airline passengers) as a cash cow to fund their taxation and/or policy failures," it said.