Silvio Berlusconi, Italy’s prime minister-elect, on Wednesday said a group of Italian businesses would make an offer for lossmaking Alitalia within weeks but warned trade union leaders to expect “painful” job cuts.

The billionaire businessman, who will be sworn in as prime minister for a third time next month, clashed with trade union leaders over who was responsible for Air France-KLM withdrawing its offer for the flag ­carrier on Monday.