MILAN (Reuters) - Six investors including U.S. funds Apollo Global Management (>> Apollo Global Management LLC) and KKR (>> KKR & Co. L.P.) are interested in the platform that will manage around 9 billion euros (£7.61 billion) in Monte dei Paschi di Siena's (>> Banca Monte dei Paschi di Siena SpA) gross bad loans, two sources close to the matter said.

The Tuscan bank is selling its 27.7 billion euro portfolio of loans to insolvent borrowers in a complex securitisation scheme, part of a broader rescue plan aimed at addressing regulatory concerns over its financial stability.

Monte dei Paschi was working with Italian investment bank Mediobanca (>> Mediobanca Group) to set up a platform to manage its portfolio and bring in a partner to improve collections.

On Friday, the Tuscan bank unveiled a plan to speed up disposal of its bad loans following a request from the European Central Bank.

The announcement came just head of industry stress test results were released that singled out Monte dei Paschi as the weakest among large European lenders.

One of the sources said Monte dei Paschi had informed potential bidders in a letter that the platform deal was going ahead though on slightly different terms than initially envisaged.

Monte dei Paschi said on Friday the platform would manage around 9 billion euros in gross bad loans -- one third of the overall loans being sold in the securisation deal.

The two sources said bidders included Cerved Credit Management (>> Cerved Information Solutions SpA), KKR in tandem with Varde Partners, Apollo Global Management (>> Apollo Global Management LLC), Cerberus, Prelios (>> Prelios SpA) together with Christofferson Robb & Company and Lone Star.

Monte dei Paschi and all other involved parties declined to comment.

(Additional reporting by Paola Arosio, writing by Valentina Za)

By Massimo Gaia