UN Secretary-General Antonio Guterres has called for Sudan to be removed from the US list of state sponsors of terrorism, as Khartoum slowly returns to the international fold.

"It is time to remove Sudan from the list of state supporters of terrorism, and to mobilise massive international support to enable Sudan to overcome its challenges," the UN chief said on Sunday during an address at the annual African Union summit in Addis Ababa.

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The US government added Sudan to its list of state sponsors of terrorism in 1993 over allegations that then-President Omar al-Bashir's government was supporting "terrorist" groups.

The designation makes Sudan technically ineligible for debt relief and financing from the IMF and World Bank.

Washington began a formal process to de-list Sudan in January 2017, but this was put on hold when Sudan's mass protests erupted a year ago. The uprising toppled al-Bashir and eventually forced the military into a power-sharing agreement with civilians.

Sudan's Prime Minister Abdalla Hamdok has repeatedly urged the West to end his country's international pariah status. He says it is the only way to save the nation's fragile democratic transition from a plunging economy.

In September, Hamdok said he was expecting a "big breakthrough" that would lead to removing Sudan from the list and unlocking desperately needed foreign aid.

"It was the former regime that supported terrorism and the Sudanese people revolted against it. These sanctions have caused tremendous suffering to our people," Hamdok, who was appointed prime minister in August, said during an address at the UN General Assembly (UNGA) in September.

"Therefore we call on the United States to remove Sudan from the list of state sponsors of terrorism and to stop punishing the people of Sudan for crimes committed by the former regime," he added.