Last checked at 
* Analysts doubt wisdom of Air Berlin wet lease deal
* Deal gives Air Berlin financial lifeline
* Eurowings expansion to help Lufthansa battle Ryanair,easyJet
* Ryanair says could now speed expansion in Germany (Adds comments from Lufthansa exec, Ryanair CEO)
By Victoria Bryan
BERLIN, Sept 29 (Reuters) - Shares in Lufthansa fell to a four-year low on Thursday on concerns its plans toboost its low-cost Eurowings brand by leasing Air Berlin planes would neither lower costs nor head off largerrivals.
Lufthansa has said it wants to turn Eurowings into Europe'sthird low-cost airline behind Ryanair and easyJet. The wet lease announced on Wednesday along withLufthansa's decision to buy the rest of Brussels Airlines willprovide planes for that expansion.
Analysts said, however, that a deal to lease Air Berlinplanes and crews for short-haul routes next summer seemed to bemore of a defensive move to stop Ryanair and easyJet gaining afoothold in Germany at the expense of Air Berlin, which has beenlosing money for years.
"It's far from clear that this expansion will help Lufthansato secure greater profitability," independent aviationconsultant John Strickland said, adding Lufthansa would stillfeel pressure from Ryanair.
Lufthansa shares were down 2.99 percent at 9.75 euros 1229GMT, having touched 9.725, its lowest level since September2012.
Shares in other European airlines also slipped on Thursdayafter OPEC agreed to curb crude oil output in a move that couldmean higher fuel costs for carriers.
Ryanair said it could grow more quickly because retrenchingby Air Berlin would result in fewer flight choices from Germany.
"The German airports will then be trying to encourageRyanair to open more routes. So I think it's likely to speed upour growth in Germany," Ryanair CEO Michael O'Leary said at anevent in Copenhagen.
Michael Gierse, fund manager at Lufthansa shareholder UnionInvestment, said the lease deal would put Eurowings in keymarkets to help block easyJet and other rivals.
"But it will only delay them and not prevent themcompletely," he said.
The so-called wet lease deal for 40 planes and crew throws afinancial lifeline to Air Berlin, which said it expectedpayments over the six-year deal to exceed 1.2 billion euros($1.4 billion).
Shares in the loss-making airline, which is 29 percent ownedby Gulf carrier Etihad Airways, were worth almost 20 eurosapiece back in 2007 but now trade for less than one euro each.
Lufthansa board member Karl Ulrich Garnadt, in charge of theEurowings division, declined to confirm the 1.2 billion eurofigure cited by Air Berlin, saying that final terms still neededto be agreed.
RBC analyst Damian Brewer said he was "perplexed" by the wetlease deal, noting Lufthansa could instead lease planes on theopen market and crew them with new staff at market rates.
Garnadt said the wet lease deal offered a quickeropportunity to grow. Lufthansa would ensure the terms fitted itsrequirements for Eurowings, where it aims for a cost basesimilar to that of easyJet, he said.
($1 = 0.8912 euros) (Additional reporting by Peter Maushagen and NikolajSkydsgaard; editing by David Clarke and Jason Neely)
