The exotic dancer at the centre of a sex trial against Italy's Silvio Berlusconi is expected to testify for the first time in court on Monday as the media tycoon bids for a fourth term as prime minister.

Moroccan-born Karima El-Mahroug -- better known by her nickname as "Ruby the Heart Stealer" -- failed to appear the first time she was called to testify and when she was called a second time her lawyer said she was in Mexico.

"The young woman will be there," her lawyer, Paola Boccardi, told AFP.

Prosecutors have accused the defence of deliberately trying to draw out the trial to avoid a verdict before the general election in February.

Berlusconi stands accused of having sex for money with El-Mahroug on several occasions in 2010 when he was still prime minister and she was just 17.

The age of consent in Italy is only 14 but sex with a prostitute who is under 18 years of age is a crime punishable by up to three years in prison.

Berlusconi is also accused of abusing his official powers by putting pressure on police to release El-Mahroug from custody when she was arrested for petty theft -- a charge that carries a maximum prison sentence of 12 years.

His defence says Berlusconi was convinced El-Mahroug was a niece of then Egyptian president Hosni Mubarak and wanted to avoid a diplomatic incident.

The 76-year-old, who is also appealing a one-year prison sentence for tax fraud handed out last year, is unlikely ever to see the inside of a prison cell however since sentencing guidelines in Italy are very lenient for over-70s.

Berlusconi has launched his sixth election bid in two decades in politics.

He denies having sex with El-Mahroug, saying that he gave her money so that she could set up a beauty parlour and avoid having to prostitute herself.

"I never had an intimate relationship of any kind with her," he said in October in his second appearance at the trial which began in April 2011.

"I was sure she was 24, as she herself said," Berlusconi said.

The billionaire said there were never "scenes of a sexual nature" at the parties he hosted at his mansion near Milan, adding: "Everything happened in front of the staff and at times my children too came in to say hello."

He said the soirees were "burlesque contests" and "elegant dinner parties."

According to transcripts of her questioning by investigators leaked in the Italian press, El-Mahroug said Berlusconi enjoyed lap dances from naked girls at parties that he called "Bunga Bunga" -- a term that has since become internationally famous.

El-Mahroug has also denied a liaison with Berlusconi but was recorded in a leaked telephone wiretap telling a friend that he had said to her: "Ruby I'll give you anything you want, I'll turn you into gold, just hide everything."

El-Mahroug is a witness for the defence and is unlikely to give incriminating testimony against Berlusconi but her comments are still eagerly awaited and will help to determine when the trial will end.

Summing up by the prosecution and the defence in the Milan courtroom are expected on January 28 and February 4 but this timetable could change.

Italians take to the polls on February 24-25 and Berlusconi has boosted his ratings since taking to the airwaves in his election campaign. A conviction just before the elections could put an end to his long political career.

El-Mahroug comes from humble beginnings, moving with her family from Morocco to a small town in Sicily in 2003. She has said that she was physically abused by her hawker father before she ran away from home when she was just 14.

According to some reports she was spotted by one of Berlusconi's ageing cronies at a beauty contest and was called to entertain the premier.

The curvaceous Moroccan has always spoken affectionately of Berlusconi, whom she has described as a kind but lonely man, forced to buy women's affection.

[Image via Agence France-Presse]