France’s former President Nicolas Sarkozy has been released from prison, three weeks into a five-year prison term, over his involvement in a criminal conspiracy.

Mr Sarkozy will be subject to strict judicial supervision and barred from leaving France ahead of an appeal trial scheduled for next year.

Mr Sarkozy is the first French ex-leader placed behind bars since World War Two Nazi collaborationist leader Philippe Pétain was jailed for treason in 1945.

Since entering prison, Mr Sarkozy has been held in a cell in the isolation wing. He had a toilet, a shower, a desk, a small electric hob, and a small TV, for which he paid a monthly fee of €14 (£12), and the right to a small fridge.

He also had the right to receive information from the outside world and family visits, as well as written and phone contact, but was in effect in solitary confinement. He was allowed just one hour a day for exercise, which he spent alone in the wing’s segregated courtyard.

Mr Sarkozy was president from 2007 to 2012.

Ever since he left office, he has been dogged by criminal inquiries, and for months, he had to wear an electronic tag around his ankle after being convicted last December for attempting to bribe a magistrate for confidential information about a separate case.

The 70-year-old former centre-right president was sentenced on October 21 to five years for conspiring to fund his 2007 election campaign with money from late Libyan leader Muammar Gaddafi.

However, his legal team immediately filed a request seeking his release.

Writing on social media after his release, Mr Sarkozy said his “energy is focused solely on the single goal of proving my innocence.”

“The truth will prevail… The end of the story is yet to be written,” he stated.

One condition of Mr Sarkozy’s release is that he does not contact any other witnesses in the so-called “Libyan dossier” or any employees of the justice ministry.

Speaking to a court in Paris via video link on Monday morning, Mr Sarkozy described his time in solitary confinement as “gruelling” and “a nightmare”.

He said he had never had the “mad idea” of asking Mr Gaddafi for money and stated he would “never admit to something I haven’t done”.

Mr Sarkozy also paid tribute to prison staff who had made his time in prison “bearable”.

“They have shown exceptional humanity,” he said.

Mr Sarkozy’s wife, the singer and model Carla Bruni-Sarkozy, and two of the former president’s sons were present in the courtroom to support him.