World Bulletin / News Desk

The United Nations on Friday said it was launching an investigation and demanding accountability after some 22 shells were fired at its compound in the town of Melut near South Sudan's Paloch oilfields, an attack that killed eight civilians.

The incident took place earlier this week. Initially a South Sudanese official had said four people were killed by two mortar bombs. But U.N. deputy peacekeeping chief Edmond Mulet said the death toll was eight and that nearly two dozen shells were fired at the U.N. peacekeeping site by combatants.

"Today it's calm," Mulet told reporters, though he added that it was not clear how long the lull would last given the recent dramatic escalation of bloodshed in the area.

"We have evacuated most of our non-essential civilian staff" from Melut, he said, noting that the 120 blue-helmeted U.N. troops, 15 police and other key U.N. staff would remain. "We will stay there in order to protect civilians."

Forces loyal to President Salva Kiir and rebels allied with former vice president Riek Machar have been fighting for nearly 18 months in the world's newest state, which seceded from Sudan in 2011. Several ceasefires have been agreed but broken.

The Security Council has threatened to blacklist anyone undermining security or interfering with the peace process in South Sudan, but it has not yet imposed worldwide travel bans and asset freezes on any officials in the country.