JUBA, Dec 21 (Reuters) - A United Nations peacekeeping helicopter was shot down in South Sudan on Friday, killing the four Russian crew members onboard, but the country's army denied the U.N.'s accusation it downed the aircraft, saying it was the work of rebels.
A U.N. source said the helicopter was on a reconnaissance mission in an area where the SPLA, South Sudan's army, has been fighting rebels led by David Yau Yau.
"The SPLA told the (U.N.) Mission that it had shot at a helicopter in the Likuangole area in Jonglei State," U.N. peacekeeping spokesman Kieran Dwyer said in a statement.
South Sudan's army denied the claims and said rebels led by Yau Yau were responsible for downing the helicopter.
"The SPLA did not shoot down the helicopter," army spokesman Kella Kueth said.
Russian news agencies reported the helicopter was Russian.
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 U.N. contract was downed today in the afternoon."
South Sudan became independent from Sudan in July 2011 but has been struggling to build up state institutions in a country awash with weapons after decades of civil war with Khartoum which ended with a 2005 peace agreement.
Human rights groups often accuse the SPLA, a loose group of former guerillas, of human rights violations and abuses. The army denies this.
Yau Yau, a former theology student, heads one of several militias fighting the government which accuses Sudan of supporting them. Sudan denies this.
A shortwave radio station with links to the Yau Yau rebellion said the group was fighting the government in reaction to abuses committed during the disarmament programme.
Russia said earlier this year it would withdraw helicopters and personnel servicing the U.N. mission in South Sudan after voicing alarm at attacks on U.N. helicopters there.
The U.N. mission in South Sudan, known as UNMISS, was created after South Sudan seceded from Sudan.