The public flogging of writer Raif Badawi has been postponed by Saudi officials on medical grounds, Amnesty International has said.

Mr Badawi, who was flogged 50 times a week ago by an Interior Ministry official, was due to face another 50 lashes on Friday.

The blogger has been sentenced to a total of 1,000 lashes and 10 years in prison for insulting Islam.

Amnesty International said a prison doctor concluded Mr Badawi's wounds had not yet healed properly and he would not be able to withstand another round of lashes.

Meanwhile, Mr Badawi's wife Ensaf Haider told news agency AFP his case has been referred to Saudi Arabia's supreme court, possibly paving the way for an appeal.

"We only knew today that Badawi's case was referred by the royal court to the supreme court nearly a month ago," she said.

Amnesty International tweeted: "Our researchers have confirmed Raif Badawi's case was referred to Supreme Court in Dec 2014 months after appeal court upheld his sentence."

However it warned he "remains at imminent risk of flogging".

Following news of Friday's postponement, the organisation's Deputy Director for the Middle East and North Africa Programme said: "Not only does this postponement on health grounds expose the utter brutality of this punishment, it underlines its outrageous inhumanity.

"The notion that Raif Badawi must be allowed to heal so that he can suffer this cruel punishment again and again is macabre and outrageous."

Saudi Arabia has come under increased pressure from Western countries over its weekly flogging of Mr Badawi, particularly since the Paris attack on Charlie Hebdo magazine, which was condemned by Riyadh.

The United States, Amnesty International and Reporters Without Borders all denounced the flogging as a horrific form of punishment, saying Mr Badawi was exercising his right to freedom of expression.

The UN human rights chief this week urged the Saudi king to pardon Mr Badawi and review the "cruel" penalty.

"Flogging is, in my view, at the very least, a form of cruel and inhuman punishment," UN commissioner Zeid Ra'ad Al Hussein said in a statement.

His wife, who sought asylum in Canada with their three children after Mr Badawi was jailed in June 2012, has also pleaded for his release

Mr Badawi, co-founder of the now-banned Saudi Liberal Network, was found guilty of insulting Islam after criticising Saudi Arabian clerics on a forum he founded in 2008.

In the past year Saudi authorities have been criticised by international rights groups for jailing several prominent activists on charges ranging from setting up an illegal organisation to damaging the reputation of the country.