As part of its electrification plans, Stellantis will build three so called 'gigafctories' in Europe, in France, Germany and Italy, though its ACC joint venture with Mercedes and TotaleEnergies, for a total capacity of at least 120 gigawatt hours (GWh) by 2030.

Two more battery plants will be built in North America with partners LG Energy Solution (LGES) and Samsung SDI.

Stellantis will phase out current productions at Termoli from the beginning of 2024, while initial operations of the new gigafactory should start in 2026, Italy's main metal-mechanic unions said in a joint statement after meeting the company.

The transition will cause an expected lay-off peak in 2025, involving around 1,000 workers, while the facility's whole workforce, around 2,000 people, is expected to be again fully employed by 2030, when operations at the new gigafactory are expected to run at full capacity, the unions said.

Gianluca Ficco of UILM said Stellantis had reassured unions that all Melfi's workers will be employed in the new gigafactory.

"This is good but not emough, clearly we want a formal and binding commitment by ACC," he said. "Then we'll have to sort out how to manage temporary lay-offs."

A spokesman for Stellantis told Reuters the company gave unions an update about development plans for the Termoli site, during an interlocutory meeting.

Unions added that production of some "premium" internal combustion engines would continue "for some years" beyond 2026.

As part of the retraining program for employees, the group will offer them the possibility to work for up to six months in the its French gigafactory in Douvrin, unions said.

(Reporting by Giulio Piovaccari; Editing by Nick Zieminski)