South African police were on Wednesday hunting for two prisoners who inexplicably escaped in the early hours from a high-security facility in the capital Pretoria, a correctional services spokesman said.

The two on the run escaped before dawn from Kgosi Mampuru II Correctional Centre prison, where the likes of paralympic athlete Oscar Pistorius and apartheid death-squad leader Eugene de Kock, nicknamed “Prime Evil” have been held.

Local media reported that the inmates had escaped by digging a hole in the wall of their cell.

In a statement, correctional services spokesman Singabakho Nxumalo identified the pair as Thabo Zacharia Muyambo from Mozambique, who is serving a life sentence for 21 counts of various crimes including rape and kidnapping, alongside Zimbabwean national Johannes Chauke who is serving 20 years for housebreaking offenses.

The spokesman declined to comment on the details of the escape from the high-wall facility which has layers of cell bars and boom gates.

But he confirmed to AFP that a hammer had been found inside the cell and a small hole was discovered high up on the wall of the cell.

The Sowetan newspaper said inmates had confirmed to the publication that the escapees used a sharp object, believed to have been stolen from the prison’s workshop, to dig a hole through the wall of their cell.

Images carried by the publication show a visible hole dug out of a wall said to be that which the inmates used to make their getaway.

According to Nxumalo authorities “are hot on their heels and these escapees shall be brought back behind bars.”

Meanwhile, the department has launched an internal probe into the mysterious escape.

The gallows at Kgosi Mampuru, known as a site of capital punishment in apartheid South Africa, is the only place in the country where executions took place.

Opened in 1902, the prison has housed former president Nelson Mandela twice during his incarceration, both times as he was awaiting trial.