MARBELLA CLUB

An Italian businessman and his wife were arrested Thursday, accused by Naples prosecutors of extorting money and favors from Prime Minister Silvio Berlusconi in return for what prosecutors described as “cooperation” in an investigation into a high-end prostitution ring in the southern city of Bari.

While the prosecutors consider Mr. Berlusconi a victim in the case, the arrests further weaken, and distract, him at a time when he is struggling to rally his fractious center-right coalition around a package of austerity measures expected to go before Parliament next week.

Few details about the extortion case were officially released. But the Naples prosecutor Francesco Greco called “credible” an account that appeared in last week’s edition of the newsweekly Panorama, which is owned by Mr. Berlusconi. Panorama said that the prime minister had paid the businessman, Gianpaolo Tarantini, about $715,000, as well as sizable monthly payments, to encourage him to strike a plea bargain if necessary to keep the case in Bari from going to trial.

In that case, Mr. Tarantini admitted that he had paid a prostitute and other women to attend parties at Mr. Berlusconi’s residences, saying he aimed to curry favor with the prime minister, a billionaire businessman himself.

A trial would have the potential of uncovering yet more unsavory details of Mr. Berlusconi’s dalliances. He is already on trial in Milan, accused of paying for sex with an under-age Moroccan woman. He denies wrongdoing.

Mr. Berlusconi told Panorama that he did not deny the payments, but that he had simply wanted to help Mr. Tarantini, “who found himself and still finds himself in very serious economic difficulty.”

“I have nothing to repent,” Mr. Berlusconi told Panorama. “On the contrary. I did nothing illicit. I limited myself to helping a desperate man without asking for anything in exchange.”

The Naples prosecutors say that Mr. Tarantini and his wife, Angela Devenuto, forced Mr. Berlusconi to pay their legal bills and housing costs, among other favors.