South Sudan has denied claims that its security services abducted and murdered two prominent critics exiled in Kenya.

Information Minister Michael Makuei said Thursday that any investigation on the execution of Mr Dong Samuel Luak and Mr Agrey Izbon Idri should start in Kenya where they were kidnapped.

“It’s not the government of South Sudan that apprehended them; it’s the Kenyan government. So, if any investigation is to be conducted, investigate Kenya, not us (South Sudan),” Mr Makuei told Eye Radio.

Mr Luak, a lawyer and a human rights defender and Mr Idri, an opposition politician, were allegedly abducted in the Kenyan capital Nairobi in January 2017 and then flown to Juba and days later executed at a detention facility in Luri, outside the South Sudan capital.

Mr Makuei was responding to human rights groups calling South Sudan to apprehend and bring to justice the killers of the pair.

“South Sudanese authorities should promptly undertake an independent and effective investigation into the apparent extrajudicial execution of two outspoken critics of the government,” said a joint statement by Amnesty International and Human Rights Watch.

A UN panel of experts on South Sudan on Tuesday published a report suggesting the critics were killed by National Security Service (NSS) officers on January 30, 2017.

“It is highly probable that Aggrey Idri and Dong Samuel Luak were executed by Internal Security Bureau agents at the Luri facility on 30 January 2017, on orders from the commander of the NSS training and detention facilities in Luri, the Commander of the NSS Central Division and, ultimately, Lt Gen Akol Koor Kuc,” reads the report.

The report added that their abduction was a collaboration between authorities in Nairobi and Juba.

Their bodies have not been found.

Kenyan Principal Secretary of Foreign Affairs Macharia Kamau declined to comment.

Under the South Sudan transitional constitution, government is charged with the responsibility of protecting its citizens both inside and outside the country.

Mr Luak and Mr Idri were the outspoken critics of South Sudan government after the country plunged into civil war in 2013.

-Additional reporting by Reuters.