ZIM has locked workers out of its head office in Haifa after union members took control of the 3,500-TEU Zim Iberia and refused to sail the vessel, reported Lloyd's List.

The company's restructuring continues to move forward causing rising management-union tensions, said the report. Unions say the state's golden share, giving it veto power, should be adjusted as part of the restructuring.

Earlier, the National Naval Officers Association and others filed a Supreme Court petition against Zim over an alleged reduction of the golden share, arguing it included a needless "reduction, amendment or impairment" of the state's share.

Following a court hearing, both parties were given two days to resolve the issue, with a deal on the table to release the vessel in exchange for a re-opening of the offices.

Zim said it was seeking meetings with the union to discuss the restructuring and the impact it will have and is hoping this will be included in the deal. The union has refused to take part in talks.