ROME (Reuters) - An alternative rescue plan for Italy's Monte dei Paschi di Siena <BMPS.MI> sponsored by veteran banker Corrado Passera will fall through if the Tuscan bank does not give data room access by the end of the week, a source close to the matter said on Monday.


Monte dei Paschi needs to raise 5 billion euros ($5.5 billion) in capital and to spin off its bad loans by the end of the year to meet a request by the European Central Bank and avoid the risk of being wound down.


Passera, a former industry minister and one-time head of Intesa Sanpaolo <ISP.MI>, has cobbled together an alternative capital-boosting plan to one presented earlier this month by Monte dei Paschi CEO Marco Morelli


The source, who spoke on condition of anonymity, said Passera had investors who were ready to invest 2 billion euros in Italy's ailing third-largest lender.


The source said Passera's proposal would no longer stand if the investors he represented were not granted access to the bank's books right away since time was running out ahead of a Nov. 24 meeting for shareholders to approve capital measures.


However, a source close to Monte dei Paschi said the bank had expressed its readiness to give Passera access to the data room on condition the anchor investors were named.

"First, also for legal reasons, the bank has asked Passera to let it know who the investors he represents are," the source close to Monte dei Paschi said.

In mid-October Monte dei Paschi gave CEO Marco Morelli a mandate to analyse Passera's proposal.

Detractors of Passera's plan say his proposal is non-binding, does not name any of the private equity funds he claims are willing to invest, and is subject to due diligence.

The world's oldest bank, which announced the main planks of its plan in late July after faring the worst in European stress tests, is set to face an uphill struggle to convince investors to back its third recapitalisation in as many years.

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(Reporting by Alberto Sisto and Stefano Bernabei, writing by Stephen Jewkes; editing by Susan Thomas)