The company said it is simultaneously studying “strategic alternatives” for its plants in Antwerp (Belgium) and Cressier (Switzerland), including their possible sale as it seeks to cope with a cash crunch.

“Petroplus intends to complete these processes in the coming months,” it said in a statement.

Petroplus, Europe’s largest independent oil refiner, recently announced it was to enforce a temporary halt at three of its refineries after banks froze a $1 billion credit facility.

The group said that the Cressier refinery was shut down, but there were strikes at Petit Couronne and Antwerp restricting operations.

Petroplus has two other refineries across Europe: Ingolstadt in Germany and in Britain at Coryton.

The French industry minister Eric Besson, interviewed on French radio station RTL, said the news was “not a surprise” since his ministry was in constant contact with the management and unions of Petroplus.

The Petit Couronne plant has 550 employees.

Credit ratings agency Standard and Poor’s on Tuesday downgraded its rating for Petroplus by three notches due to the increased risk of a default on its short-term debt.