The UK has urged Saudi Arabia not to carry out a reported sentencing of paralysis for a Saudi man as punishment for paralysing another man.
A Foreign Office spokesperson said London was "deeply concerned" by the sentence, describing it as "grotesque".
Such punishment was "prohibited under international law", the official added.
Saudi media reports earlier said the 24-year-old man could be paralysed from the waist down if he could not pay his victim £250,000 in compensation.
Ali al-Khawahir was 14 when he stabbed a friend in the back in the Eastern Province town of al-Ahsa. He has been in prison for 10 years.
The judge in the case has reportedly interpreted the Islamic law of qisas, or retribution, that Saudi Arabia follows as meaning that he in turn could face being paralysed.
Amnesty International has described this as tantamount to torture.
The sentencing is the latest example of Saudi Arabia's fundamentalist interpretation of Islamic law attracting international criticism.
BBC diplomatic correspondent Jonathan Marcus says the Foreign and Commonwealth Office's comments mark an unusually strong plea to the Saudi authorities in what is, by any standards an unusual and disturbing case.
Successive British governments have struggled at times to harmonise their concerns about human rights in Saudi Arabia with the fact that the Kingdom remains a key ally and a major customer for British weaponry, he adds.