Workers at Israel’s flag carrier ZIM Integrated Shipping Services have escalated strike action following news of its planned $4.2bn sale to Germany’s Hapag-Lloyd.

Around 800 unionised employees out of a workforce of roughly 1,000 began a warning strike on Sunday at the company’s Haifa headquarters after reports of an imminent takeover. On Tuesday, the action was stepped up to a full strike, halting operations across the company.

Union representatives said loading and unloading of vessels — including specialised ships carrying agricultural cargo — would now be stopped. Activity has also been disrupted at the ports of Ashdod and Haifa, with some ships left idle.

“We have stopped some vessels at the ports of Ashdod and Haifa and we will not let the company work on those ships until they talk with us and we are convinced they are considering the employees,” union leader Ziva Lainer Schkolnik told Reuters. She added that vessels already alongside would not be discharged.

The strike follows confirmation that Hapag-Lloyd, together with Israel’s FIMI Opportunity Fund, had won the tender to acquire ZIM in a deal signed on Monday.

Under the structure outlined, Hapag-Lloyd will acquire ZIM and then carve out its Israeli operations into a separate entity to be controlled by FIMI. The new company, to be known as “New ZIM”, will operate 16 vessels to maintain direct maritime links for Israel.

Workers said they fear large-scale redundancies under the new structure. According to union chairman Oren Caspi, employees were told that only around 120 staff would remain at the new Israeli entity, potentially leaving close to 900 workers — including many with tenure protections — without roles.

Caspi said he had expected negotiations to begin during the 48-hour warning strike but claimed neither management nor the incoming owners opened talks, prompting the escalation.

“Ships are already standing idle and damage is accumulating,” he told local media. “We will paralyze the company if necessary. They will not receive a functioning company without proper guarantees,” he told financial newspaper Calcalist.

FIMI founder and chief executive Ishay Davidi said the fund sees strategic value in maintaining a strong, independent Israeli shipping company and intends to build an advanced and efficient fleet under the new structure. Hapag-Lloyd is also expected to establish an R&D centre in Israel that could absorb some of ZIM’s technology employees.