MILAN (Reuters) -Norway's sovereign wealth fund Norges Bank and Italian asset manager Banca Mediolanum on Wednesday joined a group of Mediobanca shareholders supporting its bid for private bank Banca Generali.   

Mediobanca in April proposed buying Banca Generali from insurer Generali as it in turn seeks to stave off a buyout from Banca Monte dei Paschi (MPS). It must gain shareholders' approval to pursue the Banca Generali deal in a meeting next Monday, June 16.

A high attendance of around 80% is expected at the assembly, according to a source close to the situation. The outcome of the vote appears hard to call at this stage.

Mediobanca Chief Executive Alberto Nagel has promoted the Banca Generali deal as an alternative to the MPS plan, while MPS CEO Luigi Lovaglio stated that Mediobanca investors could support the Banca Generali deal and still tender their shares under the Tuscan bank's bid.

Italian tycoon Francesco Gaetano Caltagirone, a major shareholder in Mediobanca with a nearly 10% stake and also an investor in MPS, has criticised the industrial rationale of the Banca Generali deal and called on Mediobanca's board to delay the shareholder vote, citing insufficient details about the transaction.

Delfin, the holding company of Italian billionaire Leonardo del Vecchio's heirs and Mediobanca's largest investor with a 19.8% stake, as well as a major MPS shareholder, has not yet disclosed its voting intentions.

Norges Bank Investment Management (NBIM), which holds a 1.45% stake in Mediobanca, detailed its intentions in a table on its website. However it also voted in favour of a new share issue proposed by MPS to fund its bid for Mediobanca in April.

A group of Italian shareholders in Mediobanca, including Banca Mediolanum and collectively holding an 11.9% stake in the merchant bank, expressed support last week for the Banca Generali bid.

They signed a consultation agreement in 2018 with no restrictions on voting at the ordinary and extraordinary general shareholders' meetings.

Several institutional investors, including CalPERS, Calvert and Praxis Investment Management, have also said they would vote in favour of the Banca Generali bid.

(Reporting by Gianluca Semeraro, editing by Alvise Armellini and Keith Weir)