A disabled man sentenced to death in Saudi Arabia for attending a protest has been moved into solitary confinement in preparation for his execution, a human rights group has claimed.

Munir al-Adam was found guilty of “attacks on police” and other offences during protests in the east of the kingdom in the April 2012.

A court in the country's capital, Riyadh, sentenced the 23-year-old to death in January last year. That sentence was upheld in May 2017.

Mr Adam has impaired sight and was already partially deaf when he was arrested, but he now cannot hear in one ear at all. He claims this is a result of being badly beaten by police.

Human rights group Reprieve, said Saudi authorities had not given a reason for his move to solitary confinement, which took place on 22 June. But it said prisoners were usually transferred into cells alone prior to their execution.

Mr Adam's family had not been allowed to visit him, the group said, adding that it believed he was being held in a cell for 24 hours a day without outdoor exercise breaks.

The 23-year-old steel cable worker could be executed at any moment without his family being notified, Reprieve director Maya Foa said.

"There’s usually no date and no location given," she added. "The system is incredibly secretive and opaque, which adds to the distress for the families of those involved."

Reprieve said the case against Mr Adam – made in a secretive criminal trial – relied on a false confession he was tortured into giving. He has since retracted the statement.

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In May, the Saudi Specialised Criminal Court upheld the death sentence against Mr Adam, days after US President Donald Trump visited the kingdom.

Reprieve had called on Mr Trump to raise the issue of human rights during the trip, but he is not thought to have broached the subject.

News that Mr Adam had been moved into solitary confinement came after the Saudi interior minister announced that six people were executed earlier this week. Among them was a Pakistani man arrested for drug offences.

The deaths are thought to bring the number of executions by Saudi Arabia this year to 44.

In pictures: Protests around the world over Saudi executions Show all 7 1 /7 In pictures: Protests around the world over Saudi executions In pictures: Protests around the world over Saudi executions Protests around the world over Saudi executions Iranian and Turkish demonstrators hold pictures of Shiite cleric Sheikh Nimr al-Nimr as they protest outside the Saudi Embassy in Ankara, Turkey, In pictures: Protests around the world over Saudi executions Protests around the world over Saudi executions Kashmiri Shiite Muslims, carrying a placard with the portrait of Sheikh Nimr al-Nimr, shout slogans during a protest in Srinagar, Indian controlled Kashmir, In pictures: Protests around the world over Saudi executions Protests around the world at Saudi executions Indian police used tear smoke and rubber bullets to disperse Shiite Muslims who were protesting after Saudi Arabia announced the execution of Shiite cleric Sheikh Nimr al-Nimr on Saturday along with 46 others, including three other Shiite dissidents and a number of al-Qaida militants. In pictures: Protests around the world over Saudi executions Protests around the world over Saudi executions Shane Enright, Global Trade Union Advisor for Amnesty International, addresses demonstrators as they protest outside the Saudi Embassy in London, following Saudi Arabia's execution of 47 prisoners in one day, including a top Shiite cleric In pictures: Protests around the world over Saudi executions Protests around the world over Saudi executions Iranian protestor burn pictures of a member of the Saudi royal family in front of the Saudi Arabia embassy in Tehran, Iran, 02 January 2016. Protesters have stormed the Saudi embassy building in the Iranian capital of Tehran early Sunday amid backlash over the execution of a prominent Shiite cleric. Flammable substance was seen thrown at the building as protests gained steam over the execution of Sheikh Nimr al-Nimr. Reports states, protesters taking down a Saudi flag and burned the building. In pictures: Protests around the world over Saudi executions Protests around the world over Saudi executions Shiite Muslims hold placards with pictures of Saudi Shiite cleric Sheikh Nimr al-Nimr, whose execution in Saudi Arabia was announced Saturday, during a demonstration to condemn his execution, Sunday, Jan. 3, 2016 in Peshawar, Pakistan In pictures: Protests around the world over Saudi executions Protests around the world over Saudi executions A Kashmir Shiite Muslim shouts slogan from Indian police vehicle after he was detained during a protest in Srinagar, the summer capital of Indian Kashmir,

The oil-rich Middle Eastern kingdom has one of the highest execution rates in the world, handing down the death penalty for terror, murder, rape and armed robbery, but also for non-violent crimes including drug trafficking offences.

The country executed a record 158 people in 2015 and another 153 people last year, according to Amnesty International.

A June report by Reprieve found that 41 per cent of those executed in Saudi Arabia in 2017 were killed for non-violent acts such as attending political protests.

UN experts have called for an end to executions for non-violent offences, but authorities claim the death penalty acts as a useful deterrent to criminals.

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The most common form of execution in the kingdom, which enforces ultra-conservative Islamic laws, is beheading by sword.

Earlier this week campaigners in the UK lost a high profile case calling on the Government to stop selling arms to Saudi Arabia because of humanitarian concerns.

Campaign Against the Arms Trade had presented hundreds of pages of evidence from the UN and the European parliament, among other organisations, of air strikes in Yemen.