Italy's Autostrade per l'Italia, operator of the motorway where a bridge collapse killed 39 people, said it was confident it could prove it met contractual obligations for the concession.

Italy's government has started proceedings to strip Autostrade, which is part of the Milan-listed Atlantia group , of the concession, calling for its top managers to resign and saying it will seek to impose heavy fines.

"In relation to a plan to revoke the concession, Autostrade per l'Italia expresses confidence it will be able to prove it always correctly met its obligations as a concession-holder," the company said.

"It's a confidence based on monitoring and maintenance activities carried out in line with the best international standards. At this stage it is not possible to provide any reliable explanation on the reasons for the collapse."