BRUSSELS, Belgium — The European Union is investigating whether the proposed takeover of Brussels Airlines by Germany’s Lufthansa AG impedes fair and open competition in the airline sector.

Lufthansa has moved to take over Brussels Airlines, seeking to purchase a 45 percent stake in the holding company that owns the Belgian carrier for euro65 million ($85 million).

The deal gives Lufthansa the option to take over all of Brussels Airlines in 2011 for a price not exceeding euro250 million ($325 million).

EU Competition Commissioner Neelie Kroes says she must make sure “consumers will continue to have a competitive choice of airline services both as regards fares and routes.”