(This Oct. 26 story has been corrected to show Leonardo Maria Del Vecchio is being investigated and is not under house arrest and deletes sentence with allegation details in paragraphs 1 and 5)

By Emilio Parodi

MILAN (Reuters) - Italian police have placed four people under house arrest as part of a probe into alleged illegal access to state databases, and are investigating dozens, including Leonardo Maria Del Vecchio, son of the late billionaire founder of Luxottica, a source said on Saturday.

A lawyer for Leonardo Maria Del Vecchio said he was "eagerly awaiting the completion of preliminary investigations to be able to prove he has nothing to do with the events in question and that charges laid against him have no basis.

"He seems to be rather a victim given initial allegations and the negative outcome of the search conducted," lawyer Maria Emanuela Mascalchi said in a statement.

The alleged database access was carried out by a private intelligence business run by a former policeman, a person with direct knowledge of the matter told Reuters.

Leonardo Maria Del Vecchio is the son of Leonardo Del Vecchio, who founded Ray Ban-owner Luxottica. The tycoon died in 2022.

The illegal access to confidential data, which was allegedly sold to customers or used to blackmail businessmen and politicians, went back to at least 2019 and continued up to March 2024, a court document seen by Reuters showed.

Milan prosecutors allege the business intelligence agency tapped into three key databases: one gathering alerts over suspicious financial activities; one used by the national tax agency with citizens' bank transactions, utility bills, income statements; and the police investigations' database, the person said.

Italy's national anti-mafia prosecutor Giovanni Melillo told reporters on Saturday the probe "rang alarm bells" because it shed light on the "gigantic market for confidential information" which has acquired "a business-like dimension", ANSA news agency reported.

The probe follows another recent investigation into a large-scale data breach at Italy's top bank Intesa Sanpaolo.

(This story has been refiled to remove a picture)