Three banks opt out of Monte dei Paschi's proposed 5 bln euro cash call - source

LONDON, July 28 (Reuters) - Morgan Stanley and Italian lenders UniCredit and Intesa SanPaolo have rebuffed a proposal by Italy's third-largest lender, Banca Monte dei Paschi di Siena, to back its proposed 5 billion euro ($5.54 billion) cash call, a source familiar with the matter told Reuters.