Former Italian Prime Minister Silvio Berlusconi has said he feels "obliged" to stay in politics, a day after receiving a jail term for tax fraud. He said he wanted to "reform the justice system so that what happened to me doesn't happen to other citizens". Later Mr Berlusconi confirmed he did not want to stand for prime minister. He is expected to appeal against the conviction of inflating the price of distribution rights bought by his Mediaset group to avoid paying taxes. The media mogul has also been barred from holding office for five years. "There will be consequences," he said in an interview given on Saturday to TG5, one of the TV channels owned by Mediaset. "I feel obliged to stay in the field," he added. He went on to dismiss the case against him as "science fiction". On Wednesday, he said he would not to run again for office - confining himself to "giving advice, experience, speaking and judging without intruding". 'Intolerable harassment' Mr Berlusconi's lawyers said on Friday that he would appeal against the four-year jail sentence for tax fraud, according to media reports. The appeal will be lodged by 10 November, reports said, and could take several years. A furious Mr Berlusconi went on national television on Friday to condemn the sentence as "intolerable judicial harassment". He has long complained that he is being persecuted by left-leaning judges in Milan. "It is a political, incredible and intolerable judgement," Mr Berlusconi said on Italia 1 - another one of the TV stations he owns. Mr Berlusconi has faced a number of trials. He has in the past either been cleared, or cases have run beyond the judicial time limit. In 1997 he received a suspended sentence for false book-keeping but that conviction was reversed on appeal. In the latest case, prosecutors said that part of the money declared for the purchase of US film rights was skimmed off to create illegal slush funds, reducing tax liabilities for Mr Berlusconi's Mediaset group. The court handed Mr Berlusconi a longer sentence than the three years and eight months requested by prosecutors. However, it later announced that the sentence served would be one year due to a 2006 amnesty law aimed at reducing prison overcrowding. It ordered him and his co-defendants to pay 10m euros (£8m) in damages. Both the jail term and the ban from holding office will only take effect if the sentence is upheld by a higher court. Sex case The BBC's David Willey in Rome says Mr Berlusconi is unlikely ever to serve his sentence as the conviction first has to be confirmed by two successive courts of appeal. Those appeals could take years, he adds. In February a court threw out a corruption case against him after the statute of limitations had expired. He is also currently on trial charged with paying for sex with an underage girl and trying to cover it up. He denies any wrongdoing. Mr Berlusconi, 76, was forced to resign as prime minister of a centre-right coalition last November.