An international student from Saudi Arabia who was detained on his way to visit a US college is set to be beheaded in his home country for attending a pro-democracy rally, according to rights watchdogs.

Saudi national Mujtaba'a Al-Sweikat was 17 when he was arrested in 2012 as he attempted to fly to Western Michigan University in Kalamazoo as a prospective student.

On Friday, Al-Sweikat and 13 other prisoners accused of attending the rally, one disabled man, were transferred to the Saudi capital of Riyadh, where executions take place, according to human rights group Reprieve.

'This is an extremely worrying move from the increasingly brutal regime in Saudi Arabia,' Maya Foa, director of Reprieve, said in a statement.

Mujtaba'a Al-Sweikat is seen above. Al-Sweikat was just 17 when he was arrested in 2012 for attending a pro-democracy rally, and now faces imminent execution by beheading

'To execute a disabled man and a juvenile protester would be an appalling breach of international law and world leaders cannot stand silently by and let this happen,' said Foa.

Foa called on US President Donald Trump and British Prime Minister Theresa May to establish a 'red line' with the ostensibly US-allied regime in Saudi Arabia.

Al-Sweikat was accepted by the Western Michigan University and was flying to the US to visit the school as a prospective student when he was first detained at King Fahd Airport, according to the American Federation of Teachers.

'Mujtaba’a and others were arrested for attending a peaceful, anti-government protest, for which they were sentenced to death, a despicable violation of international law and basic humanity,' the AFT said in a statement.

Al-Sweikat was reportedly interested in studying finance in the US.

The group of prisoners set to be executed for attending the 2012 rally also includes Munir al-Adam, who is half-deaf and partially-blind after an accident as a child, according to Reprieve.

A Saudi execution is seen in this file photo. Rights watchdogs have called on the US to demand greater human rights protections from the Saudi regime, and ostensible US ally

The 14 prisoners were convicted on the basis of confessions obtained through torture, the group said.

The watchdog group said that Saudi Arabia had already carried out 14 executions in the past week, evidence, they claim, of an escalation under new Saudi Crown Prince Mohammad bin Salman.

The Saudi regime last executed prisoners on January 2, 2016, when 47 people were killed in a mass execution.

Saudi Arabia is considered a key US ally in the Middle East, and just this week US Secretary of State Rex Tillerson visited leaders in the state in an attempt to diffuse tensions between Saudis and another US ally, Qatar.