NAIROBI, July 11 -- Two Chinese UN peacekeepers were killed in renewed fighting between South Sudan's rival army factions in capital Juba, a UN official confirmed to Xinhua on Monday.

The official at the UN Mission in South Sudan (UNMISS), who asked not to be identified, said the armoured vehicle that a group of Chinese peacekeepers were travelling in on duty was hit by a mortar shell on Sunday, leading to the deaths and injuries.

"I can confirm that two Chinese were killed on Sunday evening and eight others injured. Four of the injured are in a critical condition," the UN official said.

Fighting between government troops of President Salva Kiir and forces loyal to Vice President Riek Machar resumed on Monday.

"The situation in Juba is still tense as heavy artillery and explosions could be heard," the UN official said.

The UN mission in South Sudan on Monday reported heavy fighting in Juba, including in areas close to its compounds in Jebel and Tomping.

The latest round of violence followed deadly clashes between the rival factions on Friday and Sunday in the capital city.

South Sudan's Health Ministry says at least 271 people were killed in Friday's clashes. The exact number of those killed in fighting since Sunday is not known.

There are fears that the war-torn country could descend into civil war again.

President Kiir and former rebel leader Machar have fought a civil war which broke out in December 2013 and left tens of thousands of people dead.

A peace deal signed by the two men last August under UN pressure led to the formation of a national government in April with Machar returning to his old post.