Lufthansa said in a joint statement it would initially take a 45 percent stake in SN Airholding for € 65 million ($96 million dollars) as part of a capital increase by the Belgian group.
The German airline will have an option to buy the outstanding shares from 2011 for a price of not more than € 250 million, the statement said.
Brussels Airlines is an offshoot of the bankrupt state-owned carrier Sabena and one of the few European airlines that does not belong to a major alliance. It is owned by around 40 shareholders, including the Virgin Group and several Belgian enterprises.