Opposition lawmakers on Parliament's ad hoc committee redrafting the controversial bill, reiterated a call for a so-called "public interest" defence to be introduced.
Such a clause would allow journalists who publish classified information under pain of lengthy prison sentences to argue that they had done so for the public good, and has been advocated by rights groups, lawyers and media houses.
But the idea was slapped down by ANC committee chair Cecil Burgess who said the topic was not up for discussion at this stage.
"The issue we need to consider is in which way is the bill interfering in the rights of whistleblowers. The bill says you have the right to run to the police.
"It in no way allows you to rush off the media," he said in response to proposal from the Democratic Alliance and Inkatha Freedom Party.
State law advisors had inserted safeguards for whistleblowers by amending section 38 of the bill by making it subject to the provisions of the Protected Disclosures Act and the new Companies Act.
Outcry
The bill is being redrafted following an outcry over the far-reaching powers it gave the state to classify information.
The government conceded that a provision for the classification of commercial information should be removed, along with the vague notion of national interest as a reason for keeping information secret. However, opposition parties still argue the draft law's ambit is far too wide.
On Tuesday, they objected to section 33 of the bill, which makes it an offence to make public classified information while you know or should reasonably suspect that it would "directly or indirectly prejudice the state".
IFP MP Mario Oriani-Ambrosini said the notion of prejudicing the state was firstly superfluous because otherwise the information would not have been classified in the first place.
Secondly, "prejudice to the state" seemed suspiciously similar to the now deleted notion of "national interest", he said.
The DA's Dene Smuts said the concept needed to be defined by state law advisors before lawmakers could decide whether it remained or was removed from the bill.
Deliberations on the bill, described by opponents as a bid to silence criticism of the state, is likely to continue next year.