Silvio Berlusconi in probe over teenage dancer Ruby

Italian Prime Minister Silvio Berlusconi is being investigated over his dealings with a 17-year-old nightclub dancer, prosecutors say.

According to BBC News, Berlusconi is suspected of abusing his power by trying to have the Moroccan girl - known as Ruby - released from a police cell.

Some reports say the probe includes allegations of underage prostitution.

Lawyers for the 74-year-old prime minister dismissed the claims as "absurd and groundless".

Berlusconi has previously admitted calling the police on her behalf, but says he did nothing wrong.

The dancer, who reportedly attended parties held by Berlusconi last year, has denied suggestions that she had sex with him.

She was being questioned over theft allegations when Berlusconi called the police on her behalf. He apparently told them that she was a relative of Egypt's President Hosni Mubarak.

The case came to light last November, and prosecutors at the time questioned Milan police over Berlusconi's involvement.

In a statement on Friday, Milan prosecutors said they had issued a summons to Berlusconi inviting him to come and talk to them. The prosecutors have not given details of the allegations.

The investigation is the latest in a string of legal difficulties for Berlusconi. On Thursday, a law shielding him from three unrelated trials was significantly watered down by a ruling of Italy's Constitutional Court.

He could eventually face trials for bribery and fraud related to his business dealings. Berlusconi told reporters in Berlin on Wednesday that he found the Constitutional Court hearing "laughable".

The prime minister has argued he is the target of left-wing prosecutors.