JUBA, December 17, 2013 (AFP) – Rival troops were locked in fresh battles in South Sudan’s capital on Tuesday in unrest that has killed at least 66 soldiers and sent thousands of terrified civilians fleeing since an alleged coup bid.

The fighting in the world’s youngest nation has set off alarm bells in the international community, with the United Nations urging the warring groups to refrain from ethnic violence.

President Salva Kiir on Monday accused soldiers loyal to his arch-rival, former vice president Riek Machar, of staging a coup attempt in the oil-rich but deeply impoverished nation.

A military hospital doctor said at least 66 soldiers have been killed in the fighting, which erupted late on Sunday in the capital Juba.

Sporadic clashes could be heard Tuesday in several parts of Juba, even though Kiir had announced that the city was under complete control.

A top UN envoy said at least 10,000 civilians “have received protection in the two UNMISS compounds in Juba”, and that UN staff were “taking every possible step to ensure their safety”.

The special representative of the UN secretary-general, Hilde Johnson, said it was “paramount” that the conflict did not assume ethnic dimensions.

“At a time when unity among South Sudanese is more needed than ever, I call on the leaders of this new country and all political factions and parties, as well as community leaders to refrain from any action that fuels ethnic tensions and exacerbates violence,” she said in a statement.

The African Union also said it was “deeply concerned” about the events and urged all players to show “maximum restraint” and work towards a resolution.

The heavy fighting and the alleged coup has underscored the fragility of the nation which only became independent from Sudan in 2011.

Machar — who was sacked in July — leads a dissident group within South Sudan’s ruling party, the Sudan People’s Liberation Movement (SPLM), and had been seen as the main challenger to Kiir.

The two men hail from different ethnic groups and had in the past fought on different sides during Sudan’s long civil war.

South Sudan won its independence in July 2011 after its people voted overwhelmingly in a referendum to split from the north and form a new nation.

Awash with guns after the long war, the country has struggled with ethnic violence and corruption.

An aid worker with the British charity Oxfam, Emma Jane Drew, told AFP by telephone that the situation in Juba was “very tense”.

“It’s continued shooting. Shooting could be heard all through the night. We don’t know who is fighting who,” she said, adding her team was unable to leave their compound.

Communications down, airport closed

The independent radio station Tamazuj said clashes were taking place around compounds belonging to Machar or his loyalists.

Officials have said several former government ministers have been arrested, although the whereabouts of Machar is unclear.

“So far we have lost seven soldiers who died while they were waiting for medical attention and a further 59 who were killed outside,” military hospital doctor Ajak Bullen said on Miraya FM radio.