Italy's Supreme Court has upheld a jail sentence against Silvio Berlusconi for tax fraud.

The ruling could throw the country's fragile coalition government into crisis.

Ten months after his original conviction, five judges from the Supreme Court upheld a one-year sentence against Berlusconi after his Mediaset media empire was found to have raised the price of film distribution rights artificially high, to avoid paying taxes.

Because Berlusconi is now 76, it is likely he will face house arrest or community service rather than a prison sentence.

One key part of the original sentence was annulled.

The Supreme Court ordered a review of a five-year ban on public office which will enable Berlusconi to remain as a senator and leader of his centre-right People of Freedom Party.

Berlusconi is also appealing convictions for having paid for sex with an underage prostitute and arranging for a police wire tap to be leaked and published in a newspaper.

Today's ruling is likely to place the coalition led by Prime Minister Enrico Letta under severe strain.

However, Berlusconi has pledged that his centre-right party will maintain its support for the government.

He has said he has been relentlessly pursued by leftist judges trying to subvert democracy since he stormed into politics in 1994.

This is his first definitive conviction in at least two dozen trials.