By Claudia Cristoferi and Giuseppe Fonte

Eyewear billionaire Leonardo Del Vecchio has requested clearance from the European Central Bank to double his stake in Mediobanca, raising the prospect of far-reaching changes in Italy's financial world.

Mediobanca has not had a single non-banking shareholder owning more than 10% since it was founded in 1946. Del Vecchio's move has fuelled speculation his ultimate goal could be a shake-up involving Generali, Italy's biggest insurer in which Mediobanca is the single largest shareholder with 13%.

Del Vecchio himself owns 4.8% of Generali.

Del Vecchio's holding company Delfin said on Monday it had asked the Bank of Italy on May 29 to increase its Mediobanca holding above 10% and up to 20%, adding that authorisation would take up to 60 working days.

Mediobanca declined to comment.

Mediobanca's shares were up by 8.8% by 1640 GMT, while Generali's gained 4% against a 1.7% rise in Italy's blue-chip index.

Del Vecchio, 85, has said he aims to create a stable ownership base for Generali and Mediobanca, which for decades pulled the strings in Italy's corporate world.

Under CEO Alberto Nagel, Mediobanca has been selling off assets to modernise its business model.

Last year, sources had told Reuters that Del Vecchio aimed to use Mediobanca to put pressure on Generali for possible cross-border deals.

A member of Italy's government from the 5-Star party as well as two MPs who sit on Italy's COPASIR parliamentary committee on security, speaking on condition of anonymity, on Monday said the possibility of an eventual cross-border merger for Generali raised alarm, especially now that COVID-19 was inflating Italy's already high borrowing needs.

The two MPs said COPASIR had concerns in particular about French insurer AXA, long seen as a potential partner for Generali, whose market capitalisation has shrunk to around 19.6 billion euros, roughly half of AXA's 39.5 billion euros.

One of the two parliamentarians said that a tie-up with Axa would be against Italy's national interests.

Like other Italian insurers Generali is a large holder of domestic government bonds, of which it owns around 60 billion euros.

"The pandemic has hit Italy harder than other countries," another COPASIR member, Adolfo Urso, told Reuters when asked about Del Vecchio's move. "Banks and insurers hold a large part of our public debt ... we must preserve the country's financial security."

Del Vecchio became Mediobanca's biggest shareholder in November after its decades-long partner UniCredit sold its stake.

Del Vecchio steered Luxottica towards a merger with France's Essilor to create eyewear group EssilorLuxottica. He also merged his real estate business with French rival Fonciere des Regions to create Covivio.

Del Vecchio's request for ECB permission to raise his stake first emerged in a media report on Sunday.

(Additional reporting by Gianluca Semeraro; writing by Valentina Za; editing by Alexander Smith and Jane Merriman)