Rome, Italy (CNN) -- Italian prosecutors Friday broadened an investigation into alleged tax fraud involving Prime Minister Silvio Berlusconi's Mediaset company, the largest commercial broadcaster in that country.

Mediaset was already under inquiry in Milan after it was accused of failing to pay $45 million in taxes and other fiscal crimes between 2000 and 2003.

The three-term prime minister has denied the charges, calling them politically motivated.

Further allegations of tax fraud fell under the jurisdiction of prosecutors in Rome.

Berlusconi's lawyer Piero Longo downplayed the Rome inquiry and said it was "just a minor branch of the one in Milan and was only opened because one of the companies involved is based in the capital. There's nothing new here," he told the Italian news agency ANSA.

CNN could not immediately confirm reports that the Italian leader and his son Pier Silvio Berlusconi, who is the top official at Mediaset, have been called in for questioning.

In a statement on its website, the company called the charges absurd and said it has been transparent with its budgets and tax statements.