PARIS (Reuters) - France's Vinci posted a 4.9 percent rise in first-quarter sales on Thursday, helped by acquisitions, robust concessions activity and a recovering French construction market.

Europe's biggest construction and concessions company kept forecasts that profits and revenue would rise further this year.

"The group's good performance in the first quarter, in spite of poor weather conditions, supports the previously announced outlook for 2018 of higher revenue, operating income and net income," the statement said.

Total revenue reached 8.846 billion euros (7.7 billion pounds) in the quarter. Excluding currency fluctuations and changes in scope, sales were up 2.2 percent year-on-year, Vinci said.

This fell slightly short of a median forecast of 8.943 billion euros in an Inquiry Financial poll for Reuters.

Revenue from the concessions business rose 5.9 percent, driven by an 11.8 percent jump in the airport segment, while revenue from contracting, which includes Vinci Energies, Eurovia and Vinci Construction rose 1.8 percent.

The construction business alone, which is the biggest contributor to group revenue, grew 0.2 percent in the quarter.

This reflected a 5.2 percent rise in construction in France but a 4.8 percent decline abroad. The completion of several major projects - including the Yamal gas storage project in Siberia - and the delayed start of new projects partly explained the decline in overseas construction revenue.

To counter construction sector weakness, Vinci has been expanding into faster-growing and more profitable concessions such as airports and motorways as well as in energy engineering.

This week Vinci agreed to buy the airports management portfolio of Airports Worldwide, gaining a foothold in the United States, the world's biggest air transport market, and expanding its presence in Europe and South America.

Vinci's total order book for the quarter was 31.8 billion euros, up 5 percent from the same period a year earlier.

(Reporting by Dominique Vidalon, Editing by Sarah White)

By Dominique Vidalon