Ehud Olmert, the former Israeli prime minister, has been freed from prison after being granted parole in a corruption case that reduced his sentence by a third.

Dressed in a dark-coloured T-shirt, he was seen leaving Maasiyahu prison in central Israel shortly after dawn on Sunday before being driven away.

Israel's Prison Service confirmed through its spokesperson, Assaf Librati, that Olmert was released early on Sunday morning after serving time for corruption.

He was granted early release by a parole board on Thursday and prosecutors decided not to appeal against the decision.

Olmert, who was prime minister between 2006 and 2009, was convicted of corruption and entered prison in February 2016.

He had been sentenced to 27 months.

Olmert, 71, was a longtime fixture in Israel's hawkish right wing when he began taking a dramatically more conciliatory line towards the Palestinians.

Annapolis conference

Olmert won international acclaim for relaunching peace efforts with the Palestinians at the Annapolis conference in the US in 2007, but they failed to bear fruit and the corruption charges against him have come to define his legacy.

He resigned as prime minister in September 2008 after police recommended he be indicted for corruption, but remained in office until March 2009, when Benjamin Netanyahu, the Likud leader, was sworn in to the post, which he has held ever since.

The parole board said last week that while Olmert's crimes were "severe," he was "punished for his deeds and paid a heavy price".

"The inmate underwent a significant rehabilitation process in prison and displays motivation to continue it," it said.

READ MORE: Ehud Olmert Profile

"All this significantly diminishes the risk he will deviate again from honest practice."

The decision came after Olmert was recently taken to hospital after experiencing chest pains in prison.

A picture of a gaunt Olmert in hospital robes eating from plastic utensils found its way to social media, evoking a wave of sympathy from the public as well as politicians calling for his early release.

Even after his release, Olmert could still face new criminal charges, though some Israeli news media reported that the probe is expected to be dropped.

Fresh suspicions

Olmert underwent examinations which determined he was healthy and he returned to prison after a number of days.

Last month, the state attorney's office instructed police to investigate suspicions that Olmert had smuggled a chapter of a book he was writing out of prison, an act that would constitute a felony owing to the "secretive" content, the justice ministry said.

Police had raided the office of the Yediot Aharonot publisher and seized Olmert's manuscript as well as other materials out of fears that their dissemination - prior to the mandatory censorship they would be subject to - could cause "severe security damage", the ministry said.

The investigation was ongoing, with the state attorney's office expected to announce in the coming days whether it would seek to press charges against Olmert over his conduct around the book.

Olmert's original 27-month prison term comprised 18 months for taking bribes in the early 2000s in connection with the construction of Jerusalem's Holyland residential complex, eight months for a separate case of fraud and corruption, and another month for obstructing justice.

His main convictions date back to before his time as prime minister, to the years when he served as mayor of Jerusalem and economy minister, among other positions.