The Saudi Arabian government is planning to sue a Twitter user who compared the Kingdom to ISIS over plans to execute a Palestinian poet who abandoned his Muslim faith.

Saudi justice officials have not officially said what they want to do to the social media user who was outraged over plans to kill Ashraf Fayadh.

Local newspaper Al-Riyadh quoted a government source who said: 'The justice ministry will sue the person who described ... the sentencing of a man to death for apostasy as being "ISIS-like".'

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Palestinian artist Ashraf Fayadh is facing the death penalty in Saudi Arabia after he was accused of abandoning his Muslim faith following a complaint to the country's religious police who looked at his poetry

Authorities in Riyadh, pictured, have executed more than 150 people so far this year

Saudi authorities initially sentenced Fayadh to 800 lashes, file photograph, until prosecutors appealed the leniency of the punishment and instead insisted the Palestinian poet should be put to death for his 'crimes'

However, criticising the Saudi regime within the Kingdom is particularly dangerous as it is regarded as a serious criminal offence with especially harsh penalties.

The un-named Twitter user was commenting on the death sentence handed down to Palestinian poet Ashraf Fayadh who was arrested by the country's religious police in 2013 in Abha, south west Saudi Arabia.

He was initially arrested for a book of poetry he had written and for allegedly having illicit relations with a woman.

The first court sentenced Fayadh to 800 lashes and four years in prison. Initially the three judges rejected calls for the death penalty for apostasy, but this was later overturned during a second hearing.

Saudi Arabia sentenced blogger Raif Badawi to 1,000 lashes and ten years in jail for 'insulting Islam'

This time the judges, two of whom presided over the original case, threw out defence testimony and refused to accept Fayadh's claims of repentance. This time the court agreed to impose the death penalty.

According to Human Rights Watch, Fayadh was charged with blasphemy, spreading atheism and having an illicit relationship with women, based on pictures found on his phone. He told the court the pictures were of women he had met at an art gallery.

Fayadh's friends had submitted testimony disputing the veracity of a complaint filed to the religious police by an acquaintance who accused him of making blasphemous comments about God, the Prophet Muhammad and the Saudi state during a heated discussion at a cafe in Abha, the southwestern city where the case was heard.

The one-page court document says their testimony was not accepted in the retrial because the defendant's own 'admission is the strongest evidence,' without specifying what Fayadh admitted to. He was arrested and released within a day for that argument in August 2013, says Human Rights Watch.

Just days earlier, Fayadh's friends say he may have caught the attention of religious police when he filmed one of them slapping a man on the face and forcibly pinning him against a wall in Abha. The video on YouTube has been viewed nearly 195,000 times.

While judges in the initial trial accepted Fayadh's repentance for anything deemed offensive to religion in his poetry book, judges in the retrial said the case was considered an instance of 'hadd' — specific crimes, such as apostasy, that have fixed punishments in Islam.

Shariah law is open to various interpretations, and many Muslim clerics say the death penalty is not the standard punishment for someone who leaves the faith or is an apostate, sourcing it to the Prophet Muhammad's pardon of a Muslim who had renounced Islam.

British grandfather Karl Andree, pictured, was sentenced to be flogged over breaking local alcohol laws

Saudi Arabia's ultraconservative teachings of Islam, known as Wahhabism, have drawn comparisons to some of the ideologies underpinning ISIS, which executes non-Muslims and Muslims alike for criticism of the faith.

In Saudi Arabia, however, there are no known cases in recent years of executions for apostasy, though 152 people have been executed this year for crimes like murder, rape and drug smuggling, according to Amnesty International.

Saudi Shariah Courts can issue discretionary judgments on a wide number of crimes, which also gives way to leniency. But in crimes of 'hadd', even the Saudi king cannot issue a pardon, though he can interject if there are questions around how the case was handled, according to Human Rights Watch researcher Adam Coogle, and Fayadh's friends who are familiar with the case.

In a separate case that drew widespread condemnation, including from Saudi Arabia's closest Western allies, Saudi blogger Raif Badawi was publicly flogged 50 times this year and is serving a 10-year sentence for criticizing the kingdom's powerful religious establishment online.

The judges in Fayadh's retrial sentenced him to death after one hearing, whereas the first trial lasted six hearings, Coogle said. Nowhere in the court's second judgment did it state what Fayadh said that was allegedly insulting to God and religion.

'It's really up to the whim of judges in these cases,' Coogle said.

Fayadh's brother-in-law, Osama Abu Raya, was quoted in the Saudi Al-Watan news website this week describing the artist's 2008 Arabic poetry book 'Instructions Within' as a compilation of his thoughts as a young man.

He said the book was not widely published. The court only began assessing the book last year after the man who filed the complaint against him also mentioned his poetry to the religious police. Then a fatwa council, which issues religious edicts, was asked to analyse it.

The 35-year-old had been better known for his role in the modern art world, curating an exhibition of Saudi artists at the 2013 Venice Biennale. He also curated a show in Saudi Arabia called 'Mostly Visible' that was visited by the director of London's Tate Modern, Chris Dercon.

He produced Saudi artist Ahmed Matar's presentation 'Word Into Art' at the British Museum in 2005.

Matar, speaking to the AP by telephone, said Fayadh's poetry book was about Palestinian issues. He said Fayadh, who was born and raised in Abha,'is in a weak position' because he is Palestinian and does not have the backing of a powerful Saudi tribe to mediate.

In a statement, the Palestinian Authority in the West Bank publicly appealed to Saudi Arabia to release him.

The Saudi government's human rights body says it sent representatives to meet with Fayadh in prison in Abha, where he has been under arrest since January 2014.

Fayadh's case will likely be bumped back to the appeals court and then to the Supreme Court for a final ruling.

'He's not an atheist. He is a Muslim artist and poet... He's very sensitive, he's very intelligent. He's a very good friend to major artists,' said Stephen Stapleton, founding director of the London-based Edge of Arabia, which promotes Saudi artists.

'The reality of art is you're going to have to cases like this,' he added.

Questioning the fairness of the courts is to question the justice of the Kingdom and its judicial system based on Islamic law, which guarantees rights and ensures human dignity", Al-Riyadh quoted the justice ministry source as saying. The ministry would not hesitate to put on trial "any media that slandered the religious judiciary of the Kingdom," it said.