A Milan court has rejected an attempt by former Italian prime minister Silvio Berlusconi to halt his sex-for-hire trial before Italy's general election campaign.

The ruling makes a verdict likely before the vote in February.

Mr Berlusconi's lawyer accused the court of "interfering heavily" in the Italian political campaign by refusing to suspend the trial so Mr Berlusconi can dedicate himself to campaigning for his centre-right coalition.

Niccolo Ghedini said: "A verdict will most certainly come before the election. It seems to me this is the clear intent of the court."

Mr Berlusconi denounced the trial as "a comedy, a farce, a defamatory hoax," in an interview with Sky TG24.

Prosecutors accused Mr Ghedini of merely seeking to delay a verdict in the trial, which started in 2011 when Mr Berlusconi was still in office.

He resigned seven months later, making room for Mario Monti's technical government, as the sovereign debt crisis threatened to engulf Italy.

Despite his legal woes and sex scandal, Mr Berlusconi's centre-right coalition has been gaining in the polls since he actively began campaigning.

Mr Berlusconi, 76, has also been boosted by combative televised debates with journalistic critics.

He is accused of having paid for sex with a Moroccan woman, Karima el-Mahroug, when she was 17, during racy “bunga bunga" parties with attractive young women at his villa near Milan, and then using his influence to cover it up.

Both he and Ms Mahroug have denied sexual relations.

Mr Berlusconi has apologised for hosting the parties, saying he was lonely after splitting from his second wife.

Veronica Laria left him in 2009, citing alleged dalliances with young women.

Ms Mahroug, now 20, better known as Ruby, made her first appearance in court today. She was called by the defence to testify.

The court had ordered her to return from a trip abroad and fined her €200 after she failed twice to show up.

But Mr Berlusconi's lawyers changed their strategy and decided to renounce her testimony, saying they wanted to "avoid another development in the trial that interferes with the serenity of the election campaign".

The prosecution did not include Ms Mahroug on its witness list, instead relying on her testimony during the investigation and other evidence to make their case.

Ms Mahroug's lawyer, Paola Boccardi, said her client was not angry that she did not have to testify, just "surprised that she wasn't heard".

Ms Mahroug looked relaxed, chatting with her lawyer while in court, but refused to speak with reporters after she was informed her testimony was not needed.

The judges thanked her for appearing.

Mr Ghedini had filed a motion to suspend the proceeding, citing the demands of Italy's election campaign.

The prosecution opposed the request, arguing that Mr Berlusconi was neither the formal head of his party nor its official candidate for prime minster, and that he has infrequently shown up for trial anyway, as is his right.

In their ruling, the judges said Mr Berlusconi's absences for a political campaign were a personal choice and could not be compared with having a parliamentary obligation, which has been accepted as a legitimate reason to delay a trial.

Mr Ghedini told reporters that the campaign and Mr Berlusconi's role in vetting a list of nearly 1,000 candidates was directly related to the parliament and "of great political and institutional relevance".

Mr Berlusconi's centre-right coalition is facing the centre-left Democratic Party, which is leading, and centrist parties united under a Monti agenda.

The former prime minister has long accused Milan magistrates of mounting politically inspired campaign against him; an allegation they deny.

Mr Berlusconi faces two other cases in Milan, including the appeal set to begin on Friday of his conviction for tax fraud and four-year sentence last October.

Mr Ghedini said he will seek hearing-by-hearing delays in the pending trials citing Mr Berlusconi's election commitments.

As the trial nears its close, Mr Ghedini said he wanted to call six other witnesses on his list who had not yet appeared, including actor George Clooney, Real Madrid's Cristiano Ronaldo and Ms Mahroug's mother.

Mr Clooney has said he was approached by Mr Berlusconi's team to testify about the "bunga bunga" parties, but says he only visited the residence once to seek aid for Darfur and declined an invitation to stay.

Mr Ronaldo and his lawyers have reportedly denied the Portuguese forward was even in the same city as Ms Mahroug, much less had any personal contact.

"Those reports are completely false. I do not know the woman that they are talking about. I have never met her and never got together with her. On December 29, 2009, I was in Madrid training with the team," Cristiano Ronaldo said in a press release last February.

The court is expected to decide next week on the request to hear from the additional witnesses. Two more hearings were set for 28 January and 4 February.