Some 80 per cent of the debt Sudan owes the UK is made up of interest, a report by the Observer revealed on Sunday.
A freedom of information request found that of the £861 million ($1.18 billion) Khartoum needs to pay London, £684 million ($937.6 million) is from interest.
The north African state defaulted on its loans in 1984 when Jaafar Muhammad An-Nimeiry was president. It is now under pressure to impose austerity measures, including reducing public spending, in order to see its debts cancelled.
Sudan, which two years ago saw mass protests which led to the ouster of longtime dictator Omar Al-Bashir, is now headed by a military-led transitional government. Demonstrations continue on a regular basis and government cuts threaten to destabilide the country's path towards democracy.
According to the IMF, 46.5 per cent of people in Sudan live below the poverty line. The Observer quoted Nick Dearden, director of Global Justice Now, saying: "It's really unconscionable that Britain continues to hold these loans as some form of leverage over Sudan's government today, even worse, [UK Foreign Secretary] Dominic Raab is now offering support to Sudan conditional on the government's unpopular austerity programme – which threatens to exacerbate poverty and undermine the country's fragile path to democracy."