MPs have been allocated only two days to review the Protection of State Information Bill, suggesting limited scope for changes to the contentious official secrets legislation.

In a parliamentary programme sent out on Friday, the first meeting of the ad hoc committee appointed to review the bill has been scheduled for next Wednesday.

It is due to adopt its report the next day, October 10. The report will then go to the National Assembly for consideration.

The so-called secrecy bill was approved by the Assembly in April amid warnings by lawyers that it was unconstitutional and threats by rights groups to take it on legal review.

Last month, President Jacob Zuma sent it back to Parliament for amendments instead of signing it into law, saying he believed it was unconstitutional and singling out two clauses as problematic.

But the wording of Zuma's brief to Parliament has prompted debate as to how wide a mandate to redraft he has given MPs, and hope among lobby groups that it would open at least a backdoor for substantive changes.

A fortnight ago Democratic Alliance (DA) parliamentary leader Lindiwe Mazibuko wrote to Zuma demanding he stipulate whether MPs were meant to confine their deliberations to sections 42 and 45.

She said this week she was still waiting for a reply and would take legal advice on compelling the president to provide clarity.

On Friday Mazibuko objected to the limited period set down for dealing with the bill, and said she believed any haste would be dangerous because the legislation remained flawed.

"The secrecy bill remains a highly controversial and contentious piece of legislation. It simply cannot be rushed through Parliament," she said.

"It would be highly embarrassing for the institution and for all MPs should it be found again to be unconstitutional."

Mazibuko said Parliament should postpone the meeting until clarity had been given by Zuma as to the precise terms of the review.

It would undermine this critical process to proceed with this meeting on the assumption that the referral was confined to sections 42 and 45 given how vague the president's letter to Parliament was in this regard. The terms of the referral needed to be properly clarified before the committee could begin its work.

The presidency could not immediately be reached for comment.

If changes to the bill are confined to the two sections Zuma mentioned, they will prove to be of a technical nature.

The problem with one of these provisions were pointed out to Zuma by DA MP Dene Smuts and Steve Swart of the African Christian Democratic Party.

They argued that section 45 had been rendered meaningless, and in their view unconstitutional, by a punctuation error.

The section crucially seeks to criminalise wrongful classification of information, and was seen as a hard-won safeguard against the potential abuse of the legislation to cover up state wrongdoing. But the two opposition MPs argued that the omission of a full stop after a sub-clause meant no crime was created.

The bill's many opponents have made plain that they would not be satisfied with merely correcting this.

They say despite the ANC's staged retreat from the draft law's most regressive provisions during the drafting process it still raises the spectre of excessive state secrecy reminiscent of the apartheid era.