* Vinci sees flat traffic figures on its French motorways in 2018
Vinci says "yellow vest" crisis was "very challenging"
* Vinci CEO keeps 2018 forecast of higher revenue, earnings
By Dominique Vidalon
PARIS, Jan 16 (Reuters) - Anti-government protests that have blocked some French highways stalled traffic growth on motorways run by Vinci last year, the company's chief executive said.
Vinci, Europe's largest construction and concessions group, nevertheless kept its forecasts for higher sales and earnings in 2018 and predicted that the group would see another year of growth in 2019.
Vinci reports annual earnings on Feb. 6. Besides its construction and motorways business, Vinci also runs airports and bought a majority stake in Britain's Gatwick in December.
"The 'yellow vest' crisis was very challenging. Traffic lost in the last two months of the year wiped out the increase in traffic of the first 10 months," CEO Xavier Huillard said on Wednesday.
He was speaking at a company presentation held on the site of the new headquarters tower Vinci is building for France's Saint Gobain in Paris' La Defense business district.
The "yellow vests" -- named after the fluorescent jackets French motorists must have in their cars -- have blocked roads and roundabouts since the middle of November, sometimes occupying highway toll booths and setting a number on fire.
The demonstrations began as a protest against fuel tax increases, but have morphed into a wider backlash against the economic policies of French President Emmanuel Macron.
Vinci has said that vandalism since the start of the protests will cost it "several tens of millions" of euros, not including lost revenue, as the protesters have allowed thousands of motorists on to the highways for free.
Vinci has dropped a plan to send invoices to motorists who drove through toll booths without paying and whose license plates were captured on cameras, following government criticism.
From Feb. 1, French highway toll prices are expected to rise by 1.8 percent on average, after increasing by 1.55 percent in 2018.
But with the protests continuing, the government has urged motorway operators to seek ways to cushion that planned hike in prices to help consumers struggling with low spending power.
Transport Minister Elisabeth Borne met motorways operators on Monday to discuss possible plans such as offering frequent users a subscription at a discount.
"We have made proposals to Elisabeth Borne. There will be a joint gesture from all motorway operators," said Huillard, adding that operators were set to meet the minister again later this week. (Reporting by Dominique Vidalon; Editing by Sudip Kar-Gupta/Keith Weir)