DUBLIN (Reuters) - Ryanair's <RYA.I> annual profit is set to fall for the first time in five years as intense competition in Europe pushes average fares down by around 10 percent over the winter months, Europe's largest airline said on Monday.

Two months after issuing its first profit warning in a decade, the Irish budget carrier further cut its profit forecast for the year to March to 510 million euros (432 million pounds) from 570 million euros.

The airline met analyst forecasts with a profit of 602 million euros for six months to September as a fall of 2 percent in average fares was compensated by a 22 percent rise in extra charges.

But the airline said it would be forced to hold further seat sales during the winter to keep planes full.

"The continuing fare and yield softness means that full year profits will be lower than previously guided," Chief Executive Michael O'Leary said in a statement.

(Reporting by Conor Humphries; Editing by Louise Heavens)