Thirteen South Sudanese soldiers have gone on trial accused of raping foreign aid workers and murdering their local colleague.

The incident in the capital, Juba, last July resulted in a UN report which accused UN peacekeepers of failing in their duty to protect civilians.

It happened as rival forces in the civil war clashed in the city.

The soldiers' lawyer said the allegations were untrue, Reuters news agency reports.

The incident happened in a rebel-controlled area, he added

Peace efforts have failed to bring an end to the three-and-a-half-year-old conflict, which has seen forces loyal to President Salva Kiir fighting troops who back former Vice-President Riek Machar.

The defence lawyer denies the accused were involved in the crimes 

The trial concerns an attack on the Terrain Hotel, home to aid workers from a number of international organisations.

Its manager, Mike Woodward, has been giving evidence at the military court in Juba, Reuters reports.

Between 50 and 100 soldiers entered the compound, looted the place and then raped five women, he is quoted as saying.

The defence lawyer says the compound was in a rebel-held part of the city, implying that government troops could not have been responsible.