UPDATE 1-Air France targets younger crowd with lower-cost unit Joon

* Joon aiming to hire 1,000 new staff

* To start in December with 4 European routes

* Flying to Brazil and Seychelles in summer 2018 (Adds detail and background)

PARIS, Sept 25 (Reuters) - Air France formally launched on Monday its new "Joon" lower-cost airline, which the company hopes will attract a younger clientele and restore some routes to profitability.

Air France said on Monday that Joon would start off by flying to six destinations.

Starting from December 1, Joon will fly to four cities in Europe - Barcelona, Berlin, Lisbon and Porto. It will then fly to Fortaleza in Brazil and the Seychelles from the end of March 2018.

Single fares to the European cities will start from 39 euros, while fares to Brazil and the Seychelles will range from 249-299 euros respectively.

Joon will be hiring 1,000 cabin crew staff between now and 2020, Air France chief executive Franck Terner told reporters. The airline will initially use A340 aircraft on long-haul routes and switch to more modern A350 planes from 2019.

Joon, which is targeting the 'Millennials' generation, will be run by Jean-Michel Mathieu, who has been involved with the project since the start and has held various positions in sales, digital and revenue management within the Air France-KLM group.

Air France wants to bring down costs in order to compete better against Gulf carriers on long-haul routes, and against budget carriers on short-haul routes.

Other airlines stepping up their low-cost offerings include British Airways' owner IAG, Lufthansa's Eurowings and Canada's WestJet, while problems at Ryanair have also highlighted the fight for passengers in the sector.

In July, Air France-KLM offered optimism on pricing for the rest of the year, after good travel demand resulted in better than expected second-quarter profit. (Additional reporting by Sudip Kar-Gupta; Editing by Victoria Bryan)