MILAN (Reuters) - The Benettons ushered in a change of guard at Italian infrastructure group Atlantia ATL.MI, replacing its powerful CEO with a management committee, as they move to deal with fallout from a deadly bridge collapse.

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The bridge disaster last year in Genoa claiming 43 lives brought Atlantia under heavy political pressure, with the ruling coalition 5-Star Movement calling for it to be stripped of its lucrative motorway concession.

A probe stemming from the disaster and allegations of falsified security reports on some viaducts operated by Atlantia shocked the Benetton family, who is the biggest investor in the group, and prompted it to pull support from the manager.

At a board meeting, Atlantia’s CEO Giovanni Castellucci agreed to step down after 13 years at the helm.

“We have been in state of shock since last week over what has come out from police statements,” said Luciano Benetton earlier on Tuesday.

Until a new CEO is appointed, the board has transferred executive powers to a committee made up of five directors including Atlantia’s Chairman Fabio Cerchiai and Carlo Bertazzo, who serves also as chief executive of the Benettons’ holding company Edizione.

A source close to the matter said veteran manager Gianni Mion could take a seat in Atlantia’s board further down the road.

The board also appointed the company’s CFO, Giancarlo Guenzi, as managing director.

SEVERANCE PACKAGE

The new governance, even if temporary, marks a sea-change compared with the Castellucci-led era, when the top manager dealt with all the main negotiations.

Last year he masterminded a multibillion-euro merger with Spain’s Abertis and was negotiating a potential investment by Atlantia in the rescue of flagship carrier Alitalia [CAITLA.UL].

Castellucci and other top managers at the infrastructure group are under investigation for the Genoa bridge collapse, along with officials at Italy’s transport ministry.

The outgoing manager will receive a severance package of more than 13 million euros ($14 million), Atlantia said, adding it reserved the right withhold the payment if “clear and proven evidence of gross negligence to detriment of the group should emerge”.

Atlantia's motorway unit Autostrade per l'Italia, which counts Chinese fund Silk Road and Allianz ALVG.DE among its investors, runs half of Italy’s 6,000 kms (3,728 miles) of toll roads and generates a third of Atlantia's core profit.

Castellucci, 60, was reappointed CEO at Atlantia last May with a new three-year mandate.

The management shake-up could help to mend fences with the Italian government and fend off the threat of losing its valuable motorway concession.