Villagers in Democratic Republic of Congo have discovered the remains of two UN investigators and their Congolese interpreter who went missing this month in an area engulfed in a violent uprising, a government spokesman had said.

US citizen Michael Sharp and Zaida Catalan, a Swedish national, had been in a group of experts monitoring a sanctions regime imposed on Congo by the UN Security Council when they disappeared in Kasai Central province.

Villagers found three bodies not far from where the experts group vanished, according to the government.

Police informed the authorities in the capital Kinshasa yesterday and a team including the provincial police commissioner was sent to the scene to identify the bodies.

"It's now a certainty. It is the two investigators. We identified the third body in the grave with them as their Congolese interpreter," Communications Minister Lambert Mende said.

John Sharp, the father of Michael, posted on his Facebook page that the bodies of two Caucasians had been found in a shallow grave, saying that there was a "high probability" that it was the UN officials.

"This is a message I hoped never to write," he wrote, adding that DNA tests and dental records would be used to confirm the identities of the bodies.

The United Nations said it was still examining the remains.

"We cannot, at this moment, confirm that they are the bodies of the experts. We hope to be able to provide more information on this soon," UN spokesman Farhan Haq said.

The Swedish Foreign Ministry said it would not comment on the incident as it was being handled by the United Nations.

Congo's Kasai Central region is the epicentre of the Kamuina Nsapu insurgency that has now spread to five provinces in the loosely governed Central African country.

The Kinshasa government said earlier this month the two UN officials had fallen into the hands of unidentified "negative forces" along with four Congolese who were with them near the village of Ngombe in Kasai Central.

"Going to places where few people go, asking questions that few people ask, finding out the truth, this is the work of United Nations experts," said Emilie Serralta, a former coordinator of the UN Congo group.

"This is how the reports and recommendations (guiding) the Security Council are written."