Salini, Italy's biggest building company, is looking to secure the backing of state lender Cassa Depositi e Prestiti (CDP) for its efforts to revive the country's moribund construction industry.

But CDP, expected to inject up to 250 million euros (£229 million) into the "Progetto Italia" plan, is concerned about shares in the family holding Salini Costruttori pledged to Natixis as collateral for a loan, one of the sources said.

The source did not specify how many shares were involved in the Natixis margin loan deal but said the number could be significant. Salini Costruttori owns around 67% of the listed builder.

Salini CEO Pietro Salini, a driving force behind the consolidation efforts, said that a board meeting on Progetto Italia would be held on Thursday.

"We will give you detailed information on Progetto Italia in the next few days," he told analysts in a conference call on the company's first-half results on Wednesday. Shares in the company rose 5% after the results beat expectations.

The source said CDP was worried about backing a project to create a national player that could be influenced by a French investor. Rome is keen to rescue an ailing sector that remains a major employer and driver for ambitious infrastructure plans.

In a letter sent to Salini dated July 15 and seen by Reuters, CDP said it was important that "ties currently existing on Salini shares held by Salini Costruttori be revised to the satisfaction of (CDP)", but gave no further details.

A banking source said on Wednesday the two sides were working on the idea of converting the margin loan into a term loan to avoid the risk of Natixis exercising any control.

A term loan is a loan from a bank for a specific amount that has a fixed repayment schedule.

FRENCH FACTOR

Salini, which has worked on projects ranging from expansion of the Panama Canal to a new subway line in Saudi Arabia, is launching a takeover bid for troubled rival Astaldi as a first step in a broader 1.6 billion euro ($1.8 billion) plan to consolidate the industry and create a business that can compete globally.

Corporate France has been the biggest overseas investor in Italian companies over the past decade with deals totalling $43.3 billion, Refinitiv data shows.

Some have been closely scrutinised by Rome, worried over the vulnerability of corporate champions such as Telecom Italia, in which CDP took a direct holding after Vivendi built a controlling stake.

Last month Fiat Chrysler abandoned its $35 billion merger offer for Renault, blaming French politics.

Natixis and CDP declined to comment.

Salini has said its offer for Astaldi is conditional on bagging funding commitments by Aug. 1 from CDP and banks.

Media reports have said the deadline could be pushed back to allow more time to find a solution on Natixis and iron out a few other outstanding issues such as governance.

CDP, which is almost 83% state owned, also has a board meeting scheduled for Thursday.

The Progetto Italia deal revolves around a 600 million euro capital increase with CDP stumping up 250 million euros and Salini providing 50 million euros, the banking source said.

UniCredit, Intesa Sanpaolo, and Banco BPM will inject a further 150 million euros while the rest will come from the market with guarantees from Citi and Bank of America, the source said.

(Additional reporting by Inti Landauro in Paris; Editing by Keith Weir)

By Stefano Bernabei and Stephen Jewkes