South Sudan’s President Salva Kiir says an attempted coup by soldiers loyal to his former deputy Riek Machar has been put down.
Mr Kiir said the government was in full control of the capital, Juba, after a night of heavy fighting between soldiers in the presidential guard.
A night time curfew has been put in place and a number of arrests have reportedly been made.
Several people were reported injured and hundreds have fled to a US base.
Hilde Johnson, the UN’s special representative in the country, said she was “deeply concerned” and urged “all parties in the fighting to cease hostilities immediately and exercise restraint”.
“I have been in touch regularly with the key leaders, including at the highest levels to call for calm,” she said.
The fighting in Juba broke out overnight, and intensified in the early morning, with reports of continuous gunfire and several explosions.
The city’s airport has been closed and the state TV channel SSTV went off air for several hours.
Shortly after it came back on air, SSTV broadcast an address from Mr Kiir, wearing military uniform rather than his usual civilian clothing and flanked by government officials.
He said the violence “was an attempted coup”, but that the government was now in full control and the attackers were being chased down.
He said the fighting began when unidentified uniformed personnel opened fire at a meeting of SPLM, followed by an attack on army headquarters near the university carried out “by a group of soldiers allied to the former vice-president Dr Riek Machar and his group”.
“I will not allow or tolerate such incidents once again in our new nation. I strongly condemn these criminal actions in the strongest terms possible,” he said, vowing those responsible would be have to stand “before the appropriate law institution”.