( CNN ) -- Russia 's Foreign Minister Sergey Lavrov on Saturday called on South Sudan to punish those responsible for shooting down a U.N. helicopter and taking the lives of four Russian crew members . His words come a day after the South Sudanese armed forces admitted to shooting down the helicopter in eastern South Sudan . `` We call on the government of South Sudan to carry out a full investigation of the incident , punish the guilty and take every measure to guarantee that this will never happen again , '' Lavrov said , in a statement on his website . The United Nations Mission in South Sudan said Friday four Russian crew members were killed but that there were no passengers on board the aircraft . The MI-8 helicopter went down near the settlement of Likuangole , in the state of Jonglei , in the country 's east , the U.N. mission said . It is investigating the incident . The Sudan People 's Liberation Army said it was an accident , according to spokesman Philip Aguer . He said the SPLA had contacted the U.N. mission after seeing the helicopter near an SPLA command post but had been told it had no aircraft in the area . The troops thought the aircraft looked to be the type that had dropped munitions to militias in the area , Aguer said . U.N. Secretary-General Ban Ki-Moon condemned the shooting down of the helicopter , saying in a statement that it was clearly marked as being a U.N. aircraft . Ban extended condolences to the crew members and called on the government of South Sudan to bring whoever is responsible to justice . CNN 's Zarifmo Aslamshoyeva contributed to this report .
Russia 's foreign minister calls on South Sudan to punish those responsible . Four Russians died when South Sudanese forces shot down a U.N. helicopter . South Sudan 's armed forces say the incident was an accident . Comment: