GENEVA — Switzerland's Adecco Group says French authorities have opened an investigation into the company and some of its competitors over alleged violations of French competition law.

The Zurich-based company said in a statement Thursday it is cooperating fully with the French competition authority, which informed it about the probe a day earlier.

Adecco Group, one of the world's biggest providers of human resources services, provided no more details and did not identify which of its competitors are also subject to the probe.

The company has 31,000 employees in more than 60 countries.