Renewed fighting erupted in South Sudan's capital today and forces loyal to Vice President Riek Machar said his residence was attacked by the president's troops, raising fears of a slide back into full-blown conflict in the five-year-old nation.

There was no immediate response from the government of President Salva Kiir to the statement by Mr Machar's spokesman.

Earlier, Mr Kiir's information minister, Michael Makuei, said the situation was under control and urged people to stay at home.

The two leaders, who fought each other in a two-year civil war that started in late 2013, had made a joint call for calm after clashes between rival factions broke out late on Thursday.

At least 272 people have been killed in the fighting, a health ministry source said.

Residents of the capital Juba's Gudele and Jebel districts reported heavy gunfire near the barracks where Mr Machar and his troops have their headquarters.

A witness saw helicopters overhead but did not see them firing. Hundreds of city residents sought shelter in a UN base.

The health ministry source said 33 civilians were among those killed in the latest clashes, which have fuelled fears about renewed conflict and raised concerns about the extent the two men can control their troops in the world's newest nation.

The fighting first erupted on Thursday, when troops loyal to Mr Kiir had stopped and demanded to search vehicles of Mr Machar's loyalists. That stand-off led to clashes.

Gunfire broke out again on Friday between the vice president's bodyguards and the presidential guard, while the two men were holding talks at the presidential State House to defuse tensions. Both men said at the time they did not know what had prompted the exchange of fire.

UN Secretary-General Ban Ki-moon said on Friday that the latest violence highlighted a lack of commitment to the peace process and urged the country's leaders to discipline military leaders and work together to implement the peace deal.

Responding to the developments in South Sudan, Minister for Foreign Affairs Charlie Flanagan said: "I am very concerned at the deteriorating security situation in Juba, South Sudan.

"My Department is monitoring the situation closely and our embassy team in Addis Ababa is liaising with Irish citizens in the area who are registered with the Department.

"My Department helpline can be contacted at 00353 (0)1 4082000," he added. 

Mr Flanagan said the Department's travel advice is being continuously updated and can be viewed online here and through the Travelwise app.