France's highest court has upheld a sentence against former French President Nicolas Sarkozy over the illegal financing of his 2012 re-election campaign.

He was found guilty of overspending on his campaign, then hiring a PR firm named Bygmalion to cover it up.

Sarkozy, 70, was handed the one-year sentence in 2024 of which six months were suspended, meaning they could be served by wearing an electronic tag instead of going to jail.

He has always denied all allegations.

Prosecutors in the case said Sarkozy's UMP party spent nearly double the €22.5m (£19.4m) cap on his campaign, splurging on lavish campaign rallies and events.

To hide the costs, UMP then asked Bygmalion to invoice the party, rather than the campaign.

Today's is the second definitive conviction for the former president, who was in power from 2007 to 2012.

Last December the High Court of Appeal upheld a corruption conviction and Sarkozy had to wear an electronic monitoring bracelet for six months.

Then, in September, he was sentenced to five years in jail after being found guilty of criminal conspiracy.

He spent 20 days in jail before he was released earlier in November.

An appeal trial will be held next year. Until then Sarkozy will be subject to strict judicial supervision and barred from leaving France.

Days after his release, Sarkozy's team announced the former president was writing a book about his three weeks in jail, titled "A prisoner's diary".

An excerpt from the book was published on social media: "In prison there is nothing to see, and nothing to do. I forget the silence that does not exist at La Santé [prison], where there is much to listen to. Here, the noise is, unfortunately, constant. But - like in the desert - inner life strengthens in jail."