PARIS, Aug 21 (Reuters) - French private sector activity expanded for the first time in 15 months in August, a survey of purchasing managers showed on Friday, in a hopeful sign for third quarter economic growth.
A flash estimate of the Markit/CDAF composite purchasing managers' index (PMI) -- which combines data from firms in the services and manufacturing sectors -- rose to 50.9 in August from a final reading of 47.3 in July.
A reading of 50 separates growth from contraction.
The euro zone's second largest economy grew a surprising 0.3 percent in the second quarter, data last week showed, boosting hopes that the worst is over.
"The French economy remained on the path to recovery in August, as manufacturing output rose at a robust pace while services activity showed signs of stabilisation," Markit economist Jack Kennedy said in a statement.
The factory sector moved into positive territory for the first time in 15 months, rising to 50.2 from a final July reading of 48.1.
ArcelorMittal, the world's largest steelmaker, said last month it was restarting production in the middle of August at a site in France to respond to an increase in demand. The site had shut in May after orders fell sharply.
New factory orders climbed to 53.4 from 51.3 in July, the PMI survey showed.
Activity at services companies stayed stuck below 50, but improved to 48.9 from 45.5 in July. New business rose to 50 from 45.2 in July.
However, Kennedy sounded a note of caution.
"Although recent developments are undoubtedly positive, the pace and sustainability of future growth are open to question as falls in inflation begin to unwind, government stimulus measures fade and the labour market continues to weaken," he said.
The composite indicator for employment stayed well below 50, but rose to 43.5 from 39.8 at the end of July.
Economy Minister Christine Lagarde has welcomed the improved outlook for the French economy, saying it is has been helped by 45 billion euros in government stimulus.
However, she has also warned that unemployment will continue to rise this year. (Editing by Andy Bruce)