Two South African brothers are facing indictment in the US over the sale of illegal rhino hunts, the department of environmental affairs said on Friday.

"The indictment of the owners of Out Of Africa Adventurous Safaris is noted," spokesperson Albi Modise said in a statement.

The Hawks had helped the US justice department's environment and natural resources division with its investigation into the case of Dawie and Janneman Groenewald.

"The department understands that there is a criminal case against Dawie Groenewald and 10 co-accused who are expected to stand trial in South Africa in August 2015 on 1 872 charges including racketeering, the illegal trade in rhino horns, fraud, corruption, assault and the illegal possession of firearms and ammunition."

On Thursday, the US justice department said in a statement that the brothers had been charged with conspiracy to sell rhino hunting expeditions in South Africa to defraud US hunters.

According to the US justice department, the brothers also faced US charges of money laundering and rhino horn trafficking.

"The indictment charges [the brothers] and their company Valinor Trading CC (trading as Out of Africa Adventurous Safaris) with conspiracy, Lacey Act violations, mail fraud, money laundering and structuring bank deposits to avoid reporting requirements."

According to the indictment, the Groenewalds allegedly recruited hunters at US conventions and gun shows between 2005 and 2010.

At the time, Janneman Groenewald lived in Alabama in the US.

The hunters were misled that the rhino to be killed needed to be culled for the good of the herd because they were "problem rhino".

Hunters were also told that the rhino horns could not kept by the hunters for legal reasons, and the brothers allegedly sold the horns on the black market.

"Eleven illegal hunts are detailed in the papers filed in federal court, including one in which the rhino had to be shot and killed after being repeatedly wounded by a bow, and another in which Dawie Groenewald used a chainsaw to remove the horn from a sedated rhino that had been hunted with a tranquilliser gun."

US Attorney for the Middle District of Alabama, George Beck Jr, said in the statement that in addition to breaking South African laws, the Groenewalds allegedly laundered the funds raised through Alabama banks.

"These defendants tricked, lied and defrauded American citizens in order to profit from these illegal rhinoceros hunts," he claimed.

"We will not allow United States citizens to be used as a tool to destroy a species that is virtually harmless to people or other animals."

According to a previous statement on the US justice department's website, Dawie Groenewald was previously fined for illegally importing a leopard carcass to that country.

He was fined $30 000 (around R220 050 at the time) in April 2010 for his role in the crime.

He served eight days in jail and nearly two and a half months of house arrest for contravening the US's Lacey Act, which prohibits the import of wildlife products that are illegal under the laws of the country of origin.

In the South African rhino poaching case, Dawie Groenewald was reportedly granted R1 million bail, and his wife Sariette R100 000 bail, by the Musina Magistrate's Court in Limpopo in September 2010.

National Prosecuting Authority spokesperson Nathi Mncube said on Friday that the authority was unaware of any extradition process relating to the brothers.

"Therefore [the NPA] will not speculate on what will happen if and when the request is submitted."