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* EasyJet says can't make profit forecast due to uncertainty
* Lufthansa warns core earnings will be lower this year
* Nice attack, Turkey attempted coup unsettle travellers
* EasyJet shares fall 6 percent, Lufthansa down 7.5 pct (Recasts with more background, detail, updates shares)
By Sarah Young
LONDON, July 21 (Reuters) - Last week's deadly attack inNice and attempted coup in Turkey have created fresh turmoil forEuropean airlines already grappling with the fallout of"Brexit," with easyJet saying it was unable to give an earningsforecast and Lufthansa warning on profit.
EasyJet, Europe's No. 2 low-cost carrier behindRyanair, has in the past given a forecast profit range for thetwelve months ended Sept. 30 at this time of the year, but saidon Thursday security worries, weaker consumer confidence andcurrency volatility were all dragging on its peak summer season.
Lufthansa said late Wednesday its core earningsfor 2016 would be below last year's, downgrading its previousforecast.
The German airline blamed repeated attacks in Europe whichhave dampened advance bookings for long-haul travel to thecontinent, plus what it called greater political and economicuncertainty since March.
Shares in Lufthansa slumped 7.5 percent on Thursday, whilethose of Britain-based easyJet were down 6 percent.
While Lufthansa did not refer to specifics, easyJet saidlast week's truck attack in Nice, France, that killed 84 people,and a failed coup in Turkey, would affect its fiscal fourthquarter, though it couldn't say by how much.
Asked whether this was the most difficult operatingenvironment easyJet had faced since she took the helm in 2010,Chief Executive Carolyn McCall said: "Definitely. I think thatwill be true for all airlines over the last ten years. Thereason for it is there are so many different things."
She also cited Britain's vote last month to leave theEuropean Union, plus easyJet's high level of cancelled flightsdue to air traffic strikes in France.
The "Brexit" vote has caused the value of the pound to fallby about 10 percent, making it more expensive for Britons totravel abroad, and prompted consumer uncertainty. Britain iseasyJet's biggest single market.
TURBULENT TIMES
Many European airlines have seen a hit to demand from astring of deadly attacks in Europe, including one last Novemberthat killed 130 people in Paris, as well as attacks in popularholiday destinations for Europeans such as Tunisia and Egypt.
In June, after the Brexit vote, British Airways-owner IAG also warned on profit.
Analysts currently expect easyJet's pretax profit for theyear ending Sept. 30 will drop 14 percent to 592 million pounds,according to the average of forecasts.
The company's bigger rival, Ryanair has this yearalso seen bookings dampened by security concerns, but at itslast update in May, it was still expecting profit growth of 13percent for the year ending March 2017.
Ryanair has proportionately less exposure than easyJet toboth France and Britain.
EasyJet also faces longer term concerns over its reliance onthe EU set-up to fly the routes it does, whereas Ryanair isbased in Ireland, which remains part of the EU.
Ryanair will report first-quarter earnings on July 25.
Since the Brexit vote on June 23, easyJet shares have lost athird of their value, while Ryanair's are down 17 percent.
Delta Air Lines Inc's decision to sell fewer seatsfrom the United Kingdom this winter also highlights the threatBrexit and new airline competition pose to U.S. airlines, whichhave raked in cash from transatlantic flights.
(Editing by Kate Holton and Mark Potter)
