(Adds details, Delta comment, background)
By Gavin Jones
ROME, July 11 (Reuters) - Italian infrastructure group Atlantia said it would look into the possibility of buying a stake in ailing national airline Alitalia, but it looks unlikely that it will be ready by the government's deadline of Monday.
Atlantia's board said after meeting on Thursday that it had asked CEO Giovanni Castellucci to "look into the sustainability and effectiveness of the industrial plan regarding Alitalia, including the shareholders and the management team."
Industry Minister Luigi Di Maio, who is struggling to put together a consortium of firms to save the flagship carrier for the third time in a decade, has said he wants a deal by Monday.
He has been working for months on a plan to hook it up with state-owned railway group Ferrovie dello Stato, and also has a commitment from Delta Air Lines to take a stake, but still needs to find another partner.
Atlantia's board told Castellucci to report back with his findings at a future meeting whose date was not set, making it unclear how the company could be ready in time to commit to taking a stake by Di Maio's Monday deadline.
Italian financial daily Il Sole 24 Ore said on Wednesday Atlantia was considering buying 35-40% of the perennially loss-making airline with an investment of around 300 million euros ($336 million) - the amount of the financing shortfall in the government's rescue package.
Delta's Chief Executive Ed Bastian said on Thursday the company, which is seeking to grow internationally, remains committed to investing around $100 million to acquire about 10% of Alitalia.
"I think Alitalia has a promising future with the right ownership structure in place," Bastian said.
Di Maio said this week that other investors were also still in the frame, including infrastructure group Toto Holding.
Relations between Di Maio and Atlantia have been fraught following the deadly collapse last year of a Genoa motorway bridge that was operated by one of its units.
Government ministers have blamed poor maintenance for the disaster that killed 43 people. Atlantia has denied any wrongdoing, but Di Maio has threatened to revoke its motorway concession.
Two sources from Di Maio's anti-establishment 5-Star Movement, which governs with the right-wing League, told Reuters last week that the party was prepared to settle the matter provided Atlantia accepted a number of conditions, including cuts to road tolls - a move that would cheer Italians, and possibly boost 5-Star's declining voter support.
There has also been talk that Di Maio might withdraw his threat to revoke the motorway concession if Atlantia took a stake in Alitalia. However, Di Maio has always denied a link between those two things
"I have no prejudices about Atlantia regarding Alitalia, but nobody should think that the government can take a step back regarding the issue of revoking the motorway concession," he said on Wednesday. (Reporting by Gavin Jones Editing by Alexandra Hudson)