The European Central Bank needs a few weeks to review a request by Italian billionaire Leonardo Del Vecchio to double his Mediobanca stake, ECB supervisory board chair Andrea Enria said in a newspaper interview published on Tuesday.

Del Vecchio, founder of Italian eyewear maker Luxottica, requested ECB clearance to raise his Mediobanca holding above 10% and up to 20% on June 1, bringing the prospect of far-reaching changes in Italy's financial landscape.

The move fuelled speculation Del Vecchio's ultimate goal is a shake-up involving Generali, Italy's biggest insurer in which Mediobanca is the single largest shareholder with 13%.

Del Vecchio, who has a stake of 9.9% in Mediobanca, became the major shareholder in the financial group in November when UniCredit sold its entire holding. He also holds a stake of 4.8% in Generali.

A source close to Del Vecchio has said he aims to restore the leading position Generali had in Europe in the 1990s, but his plans did not include a cross-border merger.

"Our review has only just begun and it will take a few weeks before we can complete it. We carefully assess any relevant changes in the shareholding structure, while maintaining the prospect of sound and prudent management of the bank", Enria told Italian financial daily Il Sole 24 Ore.

Mediobanca has not had a single non-banking shareholder owning more than 10% since it was founded in 1946.

(Reporting by Gianluca Semeraro, editing by Alexander Smith)