United Nations says aircraft was downed by SPLA forces in eastern Jonglei state, killing all four crew members on board.

A UN peacekeeping helicopter on a reconnaissance mission in South Sudan’s Jonglei state has been shot down by the South Sudanese army, killing all four crew members, the United Nations said.

A UN spokesman said that the South Sudanese army confirmed on Friday that it mistakenly fired at the helicopter.

South Sudan’s army had earlier denied shooting down the helicopter, saying rebels, not government forces, had brought down the aircraft.

“Earlier today, at approximately 10am South Sudan time, UNMISS reported that one of its MI-8 helicopters with four crew members on board was shot down,” Eduardo del Buey, UN Deputy Spokesperson, said.

“In subsequent communications between the Mission and the South Sudanese armed forces (SPLA), the SPLA told the Mission that it had shot at a helicopter in the Likuangole area in Jonglei State.”

Kieran Dwyer, a spokesperson for the UN department for peace keeping operations, told Al Jazeera that the crash site had been secured to complete a thorough investigation

“They were [crew members] looking for dry landing areas so that we could bring in troops to protect civilians there. We lost contact with that helicopter. We had communications with the national army, the South Sudanese army … who told us that they had shot at a helicopter in the region,” Dwyer said from New York.

“We immediately dispatched a search and rescue operation by air and we found the smoking remains of that helicopter. We’ve since confirmed that all four crew members on board were killed.”

Investigation under way

Ban Ki-moon, the UN secretary-general, has condemned the shooting down of the “clearly marked” UN helicopter.

The UN mission immediately launched a search mission, and “it has confirmed the death of all four crew members,” he said.

Earlier, the mission had said the Russian-built Mi-8 helicopter was not carrying any passengers.

Itar-tass news agency quoted a source at the Russian embassy in South Sudan as saying: “According to preliminary data, a Mi-8 helicopter owned by Nizhnevartovskavia company working under a UN contract was downed today in the afternoon”.

Russia said earlier this year that it would withdraw helicopters and personnel servicing the UN mission in South

Sudan after voicing alarm at attacks on UN helicopters there.

The UN mission in South Sudan, known as UNMISS, was created after South Sudan seceded from Sudan in July 2011, six months after a referendum agreed to under a 2005 peace deal that ended decades of civil war that killed some two million people.