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* Says profits to grow 7 pct, not 12 pct
* To add 6 mln seats in winter, up from 4 mln
* Average fares to fall by as much as 15 pct (Updates with share price rise; CEO quotes on growthopportunities)
By Conor Humphries
DUBLIN, Oct 18 (Reuters) - Ryanair cut its annualprofit forecast on Tuesday due to a weaker pound, but its shareprice rose after it said it expected to boost its market sharein the coming months by selling more tickets at cheaper prices.
Europe's largest low-cost airline, which expects sterling toaccount for a quarter of its earnings this year, said an 18percent slide in the pound against the dollar following thecountry's vote to leave the European Union had forced it to cutits profit forecast by 5 percent. Fare prices may drop bybetween 13 percent and 15 percent, it said.
The airline said it expects net profit for the year to March31 of between 1.3 billion euros ($1.46 billion) and 1.35 billioneuros, down from a previous forecast of 1.375 billion euros to1.425 billion euros.
The mean forecast of 16 analysts polled by Reuters ahead ofthe profit warning was 1.38 billion euros.
Ryanair's warning follows a number of similar statementsfrom rivals including low-cost carrier easyJet andBritish Airways-owner IAG and Germany's Lufthansa.
Chief Executive Michael O'Leary said the reduced forecast"remains heavily dependent upon no further weakness insecond-half fares or sterling from its current levels."
Having fallen 0.5 percent in early trading, Ryanair shareswere up 3.5 percent at 0933 GMT after O'Leary told analysts thathe expected Ryanair's sales and market share to grow in thecoming months.
"We are in a low-fare environment, but we like low-fareenvironments because we are the lowest-cost producer," O'Learysaid. "We are taking very significant traffic away fromincumbents ... and we see that continuing."
Ryanair's policy is to maintain passenger numbers whateverthe fare and then earn money on extras such as fees for choosingseats and on-board refreshments.
O'Leary said Ryanair planned to increase passenger numbersto 119 million from an earlier forecast of 117 million, pilingfurther pressure on competitors. Ryanair is currently receivingaround 50 planes a year from Boeing and O'Leary said he wouldconsider adding more planes than scheduled in 2018 or 2019.
Rival easyJet, which depends on the UK for aroundhalf of sales, has already cut its profit forecast by a quarterfor the year to Sept. 30 in the wake of the Brexit vote.
British airline Monarch last week was kept alive by a 165million pound ($205.18 million) bailout from investors, havingwarned in September that security concerns and the devaluationof the pound had made market conditions difficult.
"Tough trading conditions are an opportunity to makestrategic progress at the expense of weaker competitors,"Liberium analyst Gerald Khoo said in a note.
He said the warning was not a surprise as the company hadalready indicated there were risks to the downside, adding thatthe valuation more than adequately reflected the uncertaineconomic outlook.
Ryanair said fares in the six months to the end of Septemberwere also weaker than expected, falling 10 percent, but thatthis was offset by better than expected cost performance.
($1 = 0.8928 euros) (Reporting by Conor Humphries; Editing by David Goodman andLouise Heavens)
