NAIROBI: A South Sudanese general and dozens of soldiers were killed on Friday when a United Nations helicopter trying to evacuate them from the northern town of Nasir came under attack, the government said.

The United Nations said the incident was “utterly abhorrent” and a possible war crime. The U.N. crew was trying to airlift soldiers following heavy clashes in Nasir.

In a national address announcing the deaths of General Majur Dak and other soldiers, Kiir said Machar had assured him and the U.N. representative that the general would be safe and that the rescue mission should fly to Nasir to evacuate him and his men. Information Minister Michael Makuei told reporters that “approximately 27” troops were killed. A U.N. crew member was among the dead.

The U.N. in a statement urged “all actors to refrain from further violence and for the country’s leaders to urgently intervene to resolve tensions through dialogue and ensure that the security situation in Nasir, and more broadly, does not deteriorate”.