Senator Ike Ekweremadu, 60, his wife Beatrice, 56, and Dr Obinna Obeta, 50, were last month found guilty of taking a 21-year-old street vendor to the UK from Lagos to exploit his kidney.

The Old Bailey heard the organ was for the couple's daughter, Sonia, aged 25, who was cleared of the same charge.

The suspects remain in custody in the UK ahead of sentencing scheduled for 5 May in the first such case under modern slavery laws.

In his letter, Mr Obasanjo said what the couple did was “condemnable" and "can’t be tolerated in any sane or civilised society”.

But he wants the court to consider Senator Ekweremadu’s sick daughter “whose health is in danger and requires urgent medical attention”.

He also told the court to consider "the good character of the senator" while sentencing him.

It's unclear if Mr Obasanjo's intervention will make any impact.

The former president did not indicate if he was acting on behalf of the Nigerian government, but introduced himself as a soldier who was commissioned into the British Army of the West Africa Frontiers Force, and who rose to become a full general in the Nigerian Army.