A United Nations MI-8 helicopter is seen at the airport in Juba, South Sudan. The UN mission in South Sudan said on Tuesday that one of its MI-8 cargo helicopters had crashed near Bentiu. File picture: UNMISS, via AP

New York - The UN Security Council said on Wednesday that a UN cargo helicopter which crashed in South Sudan had been attacked and called for those responsible to face justice.

The Mi-8AMT helicopter from the UN Mission in South Sudan (UNMISS) went down on Tuesday near the northern oil town of Bentiu, killing three Russian crew members and injuring a fourth.

The council said in a unanimous statement put forward by Russia that it condemned the downing and that “this attack constituted a grave violation” that “jeopardised UNMISS operations”.

The 15-member council urged UNMISS and the South Sudan government to conduct a “swift, thorough and transparent investigation” and said “those responsible must be held accountable”.

South Sudan army spokesman Philip Aguer earlier said rebels “shot it down”, but provided no evidence.

Rebel spokesman Mabior Garang dismissed the claim as “malicious allegations”.

“The area in which the plane (helicopter) was reportedly shot down is government-held territory, if indeed the aircraft was shot down,” Garang said.

Bentiu has been badly damaged in heavy fighting between government and rebel forces that was sparked by a power struggle between President Salva Kiir and his sacked vice-president, Riek Machar.

A UN team was investigating the wreckage of the helicopter on Wednesday. - Sapa-AFP