Two people have been arrested in connection with a probe into materials that could be used to make a nuclear weapon, say South African police.
Mr Meyer withdrew a bail application shortly before charges were dropped
The two people were detained by specialist enforcement units in Durban and Johannesburg.
They face charges under South African laws banning nuclear proliferation.
However, charges against businessman Johan Meyer, who was arrested last week accused of trafficking nuclear material, have been dropped.
The charges - which Mr Meyer denied - had followed a lengthy police investigation, which involved the UN nuclear watchdog, the IAEA.
Officials said the case was linked to an international nuclear black market set up in the 1980s by Pakistani nuclear scientist Abdul Qadeer Khan.
According to the official charge sheet, Mr Meyer was accused of offences between 2000 and 2001 relating to the import and export of regulated goods "which could contribute to the design, development, manufacture and deployment" of weapons of mass destruction.
He was also accused of "unlawfully and wilfully possessing... nuclear-related equipment and material" from 2002 to 2004.
The old apartheid regime in South Africa had a nuclear weapons programme.
But this was closed down by the white government before it relinquished power in 1994.