James Ibori, a former governor of Nigeria's Delta state, has been ordered by a UK judge to hand over £100m ($130m) that he is accused of having stolen, the Reuters news agency reports.

Ibori was convicted in London of fraud and money laundering in 2012. After serving some of his sentence in a British prison he is now back in Nigeria.

The judge said that Ibori had to pay the money immediately or face jail once again, Reuters says.

Ibori had earlier told Reuters that he would be appealing the court's decision.