MILAN — The board of Italian carrier Alitalia says it’s filing for extraordinary administration as a result of unions’ rejection of a plan to relaunch the struggling company.

The board expressed “deep regret” Tuesday that workers overwhelmingly rejected a government-brokered relaunch plan, which had softened planned job and salary cuts. The board said the outcome made it impossible to unlock the planned 2 billion euros in investments from both managing shareholder Etihad and a consortium of Italian companies that control a 51% stake. The company will therefore need to be reorganized, the board said.

Italy’s economic development minister has said that the period of extraordinary administration, which is designed to help companies avoid failure, is expected to last about six months, during which a buyer would be sought.