Sudanese authorities said they had foiled an attempted coup on Tuesday, accusing plotters loyal to ousted president Omar al-Bashir of a failed bid to derail the revolution that removed him from power in 2019 and ushered in a transition to democracy.

Sudan's military said 21 officers and a number of soldiers had been detained in connection to the coup attempt, and a search continued for others. All affected locations under army control, it said.

The coup attempt points to the difficult path facing a government that has reoriented Sudan since 2019, winning Western debt relief and taking steps to normalise ties with Israel, while battling a severe economic crisis.

A ruling body known as the Sovereign Council has run Sudan under a fragile power-sharing deal between the military and civilians since the overthrow of Bashir, an Islamist shunned by the West who presided over Sudan for nearly three decades.

Elections are expected in 2024.

"What happened is an orchestrated coup by factions inside and outside the armed forces and this is an extension of the attempts by remnants since the fall of the former regime to abort the civilian democratic transition," Prime Minister Abdalla Hamdok said in a televised statement.

"This attempt was preceded by extensive preparations represented by lawlessness in the cities and the exploitation of the situation in the East of the country, attempts to close national roads and ports and block oil production."

The streets of the capital Khartoum appeared calm, with people moving around normally, a witness said.

Early on Tuesday morning, a witness said military units loyal to the council had used tanks to close a bridge connecting Khartoum with Omdurman, just across the River Nile.

A government source, speaking anonymously, said plotters had tried to take control of state radio in Omdurman.

The suspected instigators of the coup attempt had been arrested and were being interrogated, government spokesman Hamza Balol said on state TV, adding that the last pockets of rebellion at Al Shajara camp in south Khartoum were being dealt with.

The leader of the coup was the commander of the Armored Corps based there, Major General Abdalbagi Alhassan Othman Bakrawi, who worked with 22 other officers, defense minister Lieutenant General Yasin Ibrahim said in a statement.

On a visit to the camp shortly afterwards Sudan's top military leader, Abdel Fattah al-Burhan, condemned the coup attempt, saying it could have had "catastrophic consequences on the unity of the army, the military and the country."

"We want to take this country and hand it over to the public will, to free and fair elections," he told troops.

COUPS AND CONFLICTS

It was not the first challenge to transitional authorities. They say they have foiled or detected previous coup attempts linked to factions loyal to Bashir, who was deposed by the army after months of protests against his rule.

Those involved in the latest effort would be held to account, Hamdok said on Tuesday.

"For the first time, there are people who were arrested during their implementation of the coup," he said, repeating earlier calls for the reform and restructuring of Sudan's sprawling security apparatus.

The United States, Britain and Norway, which have led Western engagement with Sudan, as well as the United Nations, stressed their support for democratic transition.

"The United Nations condemns any attempt - whether a coup or otherwise - to undermine the democratic political transition process," the U.N. envoy to Sudan said in a statement.

Sudan has gradually been welcomed into the international fold since the overthrow of Bashir, who is sought by the International Criminal Court (ICC) over alleged atrocities in Darfur in the early 2000s.

The ICC's chief prosecutor held talks with Sudanese officials last month on accelerating steps to hand over those wanted over Darfur. read more

Despite a peace deal signed last year with some Sudanese rebels, there has been increased unrest in the western region of Darfur as well as local clashes in Sudan's east.

This week members of the Beja tribe blocked Port Sudan and highways leading to it.

Sudan's economy has been in deep crisis since before Bashir's removal and the transitional government has undergone a reform programme monitored by the International Monetary Fund.

Underlining Western support for the transitional authorities, the Paris Club of official creditors agreed in July to cancel $14 billion of Sudan's debt. But Sudanese are still struggling with rapid inflation and shortages.

Reporting by Ali Mirghani in Khartoum, Khalid Abdelaziz and Nafisa Eltahir in Cairo and Nadine Awadalla in Dubai Writing by Aidan Lewis and Tom Perry; Editing by Andrew Heavens, Alistair Bell and Cynthia Osterman