PARIS—Elan Partners, the holding company that owns fast-growing French public relations consultancy Agence Elan, has acquired a partial stake Brussels-based consultancy Euralia as part of its continuing international expansion.

Euralia was founded 20 years ago by Bruno Dupont to represent the interests of French companies to European policy makers. Two years ago, the firm opened a Paris office, and today it has a team of 16 employees specialized in regulatory and policy monitoring, lobbying, the identification of EU programs and funds, and public affairs training.

Now Elan Partners and Euralia chief executive Didier Sallé have acquired the firm from its founder, with Sallé continuing to provide day-to-day management.

The acquisition follows the opening of an Agence Elan London office last year and means that the four-year old firm now has income of around €8 million. The new holding company—owned by Elan founders Marion Darrieutort, Nicolas Narcisse and Jean-Pierre Rousset—will further fuel the firm’s international expansion and its diversification into additional service offerings.