* Antitrust probe to involve Mediobanca-Generali ties
* Unipol-Fondiaria merger would create dominant positions
* Probe should be wrapped up in 45 days (Releads, adds detail, background)
ROME/MILAN, April 26 Italy's antitrust agency suspended the planned merger of troubled Italian insurer Fondiaria-SAI and peer Unipol on Thursday in order to investigate potential risks to competition from the tie-up, further clouding prospects for the deal.
The agency said in a statement the suspension was to prevent "the next steps in the operation creating effects hard to reverse with regard to the capital of the companies involved".
In January top investment house Mediobanca brokered a complex deal for Unipol to save the loss-making Fondiaria-SAI via a four-way merger involving three capital hikes.
The capital hikes were scheduled to be launched in May. The antitrust probe should be wrapped up in 45 days but the agency has the option of taking a further 30 days for decisions.
A merger of Unipol and Fondiaria "risks creating or reinforcing dominant positions in various branches of the insurance sector," the agency said.
A takeover of Fondiaria by Unipol would create a company with 32 percent of Italy's non-life insurance sector and around 37 percent of its motor insurance business, able to compete with Generali.
The agency said it would also be looking at the relationship that would be created between the new merged entity and Mediobanca, as well as examining the ties between Mediobanca and Italy's biggest insurer Assicurazioni Generali.
Mediobanca, which has a debt exposure to Fondiaria-SAI of over 1 billion euros, controls Fondiaria's bigger rival Generali.
Unipol and Fondiaria could not be reached for a comment.
Fondiaria is at the centre of a widening judicial investigation involving Salvatore Ligresti, the head of the family that controls Fondiaria parent Premafin.
As part of that probe, Italy's tax police seized a 20 percent stake in Premafin last week.
Italian private equity funds Palladio Finanziaria and Sator have launched a rival bid for the Fondiaria-SAI group which is opposed by the insurer's creditor banks Mediobanca and UniCredit . (Reporting by Alberto Sisto, Gianluca Semeraro and Stephen Jewkes; Editing by Mark Potter)