The Namibian government on Friday called for bids from trophy hunters to kill three endangered black rhinos, despite fierce global criticism over previous auctions.

An American hunter last year paid $350,000 to shoot one of the prehistoric beasts with a high-powered rifle, with government officials on hand to ensure he killed the correct animal.

Since 2012, Namibia has sold licences each year to kill individual rhinos, saying the money is essential to fund conservation projects and anti-poaching protection.

It says the only rhinos selected for the hunts are old individuals that no longer breed and that pose a threat to younger rhinos.

On Friday, the environment ministry advertised three black rhinos available for the hunting season which ends in November.

The advertisement offered discounts to Namibian-owned companies or those employing a Namibian−registered professional hunter.

Environment ministry spokesman Romeo Muyunda defended the auction, telling AFP: "We feel we are doing the right thing.

"As a country we have our own legislation and we are not doing anything contrary to any law. As a matter of fact, our constitution allows us to empower our own people,” he said.

"We are hoping to get enough money from this auction but we also do not want it to be controversial like in the past,” he said.

In neighbouring South Africa, nearly 1,200 rhinos were killed by poachers last year in a slaughter driven by demand for powdered rhino horn in some Asian countries, where it is seen as medicinal.