MILAN (Reuters) - Italian police said on Thursday they had uncovered a billion-euro scam to obtain illegal tax credits from government incentives that were meant to encourage home renovations.

Finance Police (GdF) in the northwestern town of Savona said they had placed 311 people under investigation and seized tax credits worth one billion euros ($1.09 billion) after searching 85 companies in 10 Italian regions.

"This is the largest operation of its kind in Italy to date," a local GdF provincial command officer told Reuters by phone, declining to give his name.

Italy has introduced a number of schemes in recent years aimed at boosting the economy, including the Superbonus, which allowed homeowners to deduct 110% of the cost of energy-saving work from their taxes, or use the massive tax credit as a form of payment when dealing with builders or banks.

Investigators say the initiatives are easily abused and Prime Minister Giorgia Meloni's government revealed last month that it had uncovered 16 billion euros of fraud tied to the various bonus schemes.

On Tuesday Italian lawmakers approved measures to curb the costly incentives, which besides attracting criminals have also proved far more popular than expected with legitimate homeowners, punching a hole in state accounts.

In Thursday's operation, police said they had found that the billion euros of tax credits "were completely non-existent, as they were obtained through the use of false invoices for work that was never done".

The investigations, according to the police, subsequently uncovered how the alleged scam in the province of Savona had been replicated nationwide by other firms, some of which proved to be empty shell companies.

($1 = 0.9198 euros)

(Reporting by Emilio Parodi, editing by Christina Fincher)