Updated

Sweden's prime minister says the United Nations and Congo must investigate after three bodies, including those of Swedish and American investigators with the United Nations, were found in central Congo.

Stefan Lofven says he learned with "great sorrow and dismay" that the bodies of Swedish national Zaida Catalan, American Michael Sharp and their interpreter Betu Tshintela were found this week.

They went missing March 12 along with driver Isaac Kabuayi and two motorbike drivers while looking into large-scale violence and alleged human rights violations by the Congolese army and local militia groups.

Lofven said Wednesday that Catalan worked "tirelessly for peace and justice," adding Sweden was "naturally ready to assist" in investigating their death.