Lufthansa has agreed to buy the 20 percent of bmi it does not yet own from Scandinavia's SAS, boosting its holding in the British carrier to 100 percent.
Germany's flagship carrier had previously said it was in talks to buy the stake and had said it aimed to come to an agreement with SAS by the end of this year.
Lufthansa said on Thursday it agreed to pay about GBP19 million pounds (USD$30.6 million) for the stake, plus another GBP19 million to cancel a 1999 shareholder agreement relating to bmi.
If Lufthansa decides to sell bmi, as a whole or in parts, it will pay a further unspecified sum to SAS within the next two years, Lufthansa said.
It has said it is considering all options for bmi, ranging from keeping the company to a complete sale. Media reports have said that bmi has attracted the interest of 12 potential buyers.
British Airways' CEO Willie Walsh confirmed in a newspaper interview this month that he would be interested in bmi if Lufthansa decided to sell the carrier.
Bmi, which traces its roots to a 1938 flight school for Royal Air Force pilots, carried 10 million passengers in 2008, generating revenues of GBP1.04 billion (USD$1.7 billion). It posted a full-year loss of almost GBP100 million.