* Final hearing set for Feb. 4, barring further delays
* Berlusconi faces 15 years in prison, but unlikely to go
* Elections most likely to be on Feb. 17 or Feb. 24
* Berlusconi's PDL trails PD party by about 15 points
MILAN, Dec 17 (Reuters) - A Milan judge set the date for the final hearing of Silvio Berlusconi's sex trial on Monday, making a verdict possible before elections early next year when the media magnate will seek his fifth term as prime minister.
Judge Giulia Turri said, barring further delays, the last hearing would be on Feb. 4. The most likely election dates are Feb. 17 or Feb. 24.
Nine days ago Berlusconi announced that he would run for office again. Polls show that his People of Freedom (PDL) party trails the Democratic Party (PD) by about 15 percentage points.
He faces a maximum sentence of 15 years in prison, but would not go unless the verdict was carried at two appeals allowed by Italian law, usually a lengthy process.
A week ago, the main witness - Karima El Mahroug - failed to appear in court, delaying the trial by a month. El Mahroug, better known by her stage name "Ruby the Heartstealer", later told her lawyer she was on holiday in Mexico.
Prosecutor Ilda Boccassini told the court that El Mahroug's absence was part of a engineered "strategy" to delay the verdict until after the vote.
Turri said in court on Monday that El Mahroug's absence last week was "unjustified".
Berlusconi is charged with paying for sex with El Mahroug at parties thrown in his lavish villas when she was under 18, which is the minimum legal age for prostitution in Italy.
The trial, in which dozens of women have described so-called "Bunga Bunga" parties at Berlusconi's residences, is the most sensational of his legal cases and has drawn huge media attention in Italy and abroad.
Berlusconi denies all charges and El Mahroug, who is now 20, has said she never had sex with him.
On Sunday, he apologised to Italians, saying he had thrown the parties because he felt lonely during his divorce proceedings and after the death of his mother. He then announced his engagement to a woman almost 50 years his junior, Francesca Pascale.
In the interview on his own Canale 5 channel, Berlusconi again described the parties as "elegant" dinners instead of the debauched affairs with pole-dancing prostitutes described by witnesses.
The centre-right leader is also accused of abusing his powers when he was prime minister to have El Mahroug released from police custody when she was held over theft allegations.
Berlusconi was sentenced to four years in jail for tax fraud in October, and can appeal twice before that sentence becomes definitive. He was convicted of corruption and false accounting three times in the 1990s before being cleared by higher courts.
If any verdict became definitive he would be barred from holding office for five years.