In the running are a group consisting of U.S. private equity firms Advent International and Bain Capital with Italy's Clessidra; a group including Britain's BC Partners [BCPRT.UL] and Cinven [CINV.UL]; and a third private equity team comprising Permira [PERM.UL] and CVC Capital Partners [CVC.UL], the sources told Reuters.

U.S. private equity firm Hellman & Friedman, whose 2.05 billion euros bid had made it the likely frontrunner, has dropped out of the race, they said.

In an effort to further its chances, Hellman & Friedman held talks with Edizione Holding, the holding company of Italy's Benetton family, about a possible joint bid, a third source familiar with the matter said.

Advent, Bain, BC Partners, Cinven, Clessidra, CVC, Hellman & Friedman and Permira had no comment.

The first two sources said the bidding groups were due to embark on the "data room" phase, where they comb through the accounts of ICBPI which earns fees on payment, clearing and credit card services provided to Italy's cooperative "popolari" banks.

Under pressure to strengthen their capital base and loath to tap shareholders for more cash, the cooperative banks have resorted to selling their profitable ICBPI asset.

Italy's popolari banks are under the spotlight after the government approved a long-awaited reform of their governance earlier this month.

The changes, which affect only the larger banks, seek to make them more appealing to potential investors and are expected to trigger defensive mergers.

ICBPI, which reported 2014 core earnings of 167.6 million euros, is controlled by 11 popolari led by Credito Valtellinese (>> Banca Piccolo Credito Valtellinese Sc) and Banco Popolare (>> Banco Popolare Societa Cooperativa).

The banks stand to book a capital gain from the sale.

The group of owners, which also includes unlisted Banca Popolare di Vicenza [BPVIC.UL] and Veneto Banca [VBANCT.UL], shortlisted the three bidders based on the size of their offers and their business plans for the services firm.

(Additional reporting by Valentina Za and Stephen Jewkes; Editing by David Holmes)

By Francesca Landini and Pamela Barbaglia