Two United Nations (UN) experts have gone missing since Sunday (12 March) in the Democratic Republic of Congo (DRC)'s restive Kasaï region.

The Kasaï, in the heart of the DRC, has been plagued by deadly violence between the Congolese security forces and a local militia, Kamwina Nsapu, since August 2016.

The experts – Michael Sharp, a US citizen, and Zaida Catalan, of Swedish nationality – had been instructed by the UN Security Council to investigate armed groups, human rights violations and possible violations of an arms embargo in the country under the Resolution 1533 of 2004, according to UN-funded Radio Okapi.

Congolese authorities in a statement on 13 March confirmed the two UN investigators had been in the Kasaï- Central province for five days when they were abducted near the village of Ngombe in the Bokonde area with their three taxi-motorcycle drivers and their interpreter.

The experts were "abducted in circumstances not yet elucidated", the Congolese government said, without identifying the abductors, who allegedly took the men in the forest.

Government spokesman Lambert Mende confirmed that the judicial authorities of Kasaï Central "have just opened an investigation to identify the perpetrators of the kidnappings and bring them before the competent courts".

In its communiqué, the government insisted that the UN experts were travelling in the province "without the local authorities being informed". The UN's peacekeeping mission to the DRC (Monusco), however, said it did not wish to comment on Mende's statement until it obtained results of its investigation.

Charles-Antoine Bambara, director of the Department of Public Information for Monusco on 13 March added, "the UN and Monusco are doing everything possible at the moment to localise these two experts".

Monusco confirmed no group had so far claimed responsibility for the abduction, nor had the mission officials received any demand for ransom.