Staff at Fiat’s Mirafiori plant in Turin yesterday approved a tough deal on working conditions that is to save their factory and prove key to the future of the new Fiat-Chrysler auto giant.

According to a final tally of the vote, those supporting the deal obtained 54 per cent.

Turnout was 94 per cent, with 5,119 of the plant’s 5,431 employees taking part.

Counting went on all night after the polls closed on Friday.

Production line workers mostly voted against the deal, but the other employees carried the day. Giovanni Centrella of the UGL union hailed “the sense of responsibility” of employees at Mirafiori “which has saved tens of thousands of jobs”.

Meanwhile, Giorgio Airaudo of Fiom, the metal workers branch of the CGIL union which campaigned against the deal, saluted “the great courage” of those who voted “no”.

Fiat president John Elkann assured the workers of the “total support” of the company’s founding Agnelli family. He called on them to “confront the challenges to come in a constructive manner”.

The Mirafiori plant has been at the heart of Fiat for more than 70 years, but Fiat-Chrysler boss Sergio Marchionne had threatened to close the factory and take production to the US if workers voted against the deal.

Marchionne’s proposal is to bring one billion euros in investments to Mirafiori, which would start producing Chrysler Jeeps and impose tougher working conditions on staff.

The deal ignited a fierce political debate in Italy after Prime Minister Silvio Berlusconi earlier this week said Italian companies “would have good reason” to leave Italy if the proposal was voted down.