Story highlights Prosecutor: Berlusconi, Italy's former PM, should be sentenced to six years in prison

Belusconi is accused of sex with an underage prostitute "Ruby the heart-stealer"

Berlusconi's defense has asked for at least a week to prepare its closing argument

Silvio Berlusconi, Italy's controversial former prime minister, should be sentenced to six years in prison and banned permanently from holding public office over the "Ruby the heart-stealer"case, prosecution said Monday.

They made the argument as they summed up their case in Milan against Belusconi -- accused of sex with an underage prostitute and abuse of office to get her freed from jail in 2010 when she was arrested and accused of theft.

Berlusconi's defense has asked for at least a week to prepare its closing argument after prosecutor Ilda Boccassini summarized her case on Monday.

Berlusconi had sex 13 times with underage dancer Karima el Mahroug, nicknamed "Ruby the heart-stealer," prosecutors say. El Mahroug has said she never had sex with Berlusconi and that she lied to him about her age, telling him she was 24.

Berlusconi -- who served on and off as prime minister between 1994 and 2011 -- is arguably one of the most colorful and controversial figures in the lively history of Italian politics. For years, he has been entangled in fraud, corruption and sex scandals that have often reached Italian courts.

A tax evasion case was the first one that resulted in a conviction after he was sentenced last October.