Authorities have arrested a Congolese colonel who failed to disclose that he had met with two UN experts just two days before they were brutally murdered, officials said on Friday.

The arrest of Colonel Jean de Dieu Mambweni came shortly after a hearing into the March 2017 killings of American Michael Sharp and Swedish national Zaida Catalan in Kananga.

Democratic Republic of Congo has blamed the killings on the Kamwina Nsapu militia active in the central Kasai provinces. However, critics note that the experts had been investigating alleged human rights abuses and have said security forces may have been involved, which the government denies.

Mambweni initially said that he had met twice with the UN experts in January and then for a final time briefly at his home on March 9.

However, in a newly introduced recording played at the hearing on Thursday, a man can be heard saying the date, March 10, during a prayer before a meal shared with Sharp and Catalan, according to the UN-backed Radio Okapi.

A man's voice says: "Take this number. It's Mr Betu. Can I inform him?" He then can be heard calling Betu on the phone.

Mambweni acknowledged when questioned that the voice on the recording was his.

He had previously said he did not put the UN experts in touch with Betu, the interpreter who accompanied them on their journey to Bunkonde.

Sweden's public broadcaster SVT says the recording also indicated that Mambweni was in contact with an unnamed person who lured the experts to the place where they were killed.

The colonel insisted he had nothing to hide and simply could not remember everything.

"The Kamuina Nsapu militia had spread with breathtaking speed. We were consumed by the volume of work," he said.