The police said on Monday they had arrested a suspect for allegedly attempting to sell rock art that may have been ripped from the wall of a cave.
The Hawks made an arrest last week following a tip-off about the sale of a primeval painting made by the San people, southern Africa's earliest inhabitants.
The search led to the discovery of the artefact and the arrest of its alleged trader in Port Shepstone, KwaZulu-Natal, the police said.
A 48-year-old suspect appeared before a magistrate on Monday and was later released on R1 000 bail pending further investigations.
"The San art rock may have been chiselled from a sandstone cave," Hawks spokesperson Philani Nkwalase told AFP.
Previously called Bushmen, the San people have a presence in South Africa that dates to more than 25 000 years.
They bequeathed a breathtaking collection of paintings in caves and mountainsides, some of which have Unesco World Heritage Site status.
The seized artefact depicts two antelopes and a man holding a stick or a spear. The sale price was not disclosed.
The police have called in archaeologists and forensic scientists.
"The experts should be able to tell us how old it is and who the buyers would be," Nkwalase said.