Government is refusing to comment on an investigation into Department of Agriculture, Forestry and Fisheries officials allegedly aiding international sea poachers to escape South African custody.
The investigation, which involves Interpol, is into the December "disappearance" of two fishing trawlers from Cape Town harbour.
Samudera Pasific No 8 and Berkat Menjala No 23 were part of a flotilla of 10 tuna trawlers impounded in November after they allegedly fished illegally in South African waters.
At the time of the impound, the vessels were described by fisheries department officials as slave ships.
The crew - from Taiwan and Indonesia - were allegedly living in appalling conditions, after not being paid for years.
Minister Tina Joemat-Pettersson and her department failed to respond to repeated requests for comment.
After the ships escaped, Interpol was notified and a purple notice was issued.
Purple notices are used to seek or provide information on modus operandi, objects, devices and concealment methods used by criminals.
Interpol said the fleet was impounded on suspicion of various fishing offences and fraudulently sharing the same fishing licence.
An Interpol source yesterday said it was investigating whether the ships' owners were involved in pillaging Africa's shoreline.
"A larger investigation into an international sea wildlife poaching and smuggling syndicate and the involvement of these suspects is under way," said an Interpol official who spoke on condition of anonymity.
"The operation specialises in abalone poaching," he said.
"How they escaped custody needs to be explained."
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