Speaking to the Parliamentary Press Gallery Association in Cape Town last night, Motlanthe said asking the highest court in the land to pronounce on the constitutionality of the bill before Zuma signed it "was the way to go".

"We would not hesitate to say to the president 'Refer it to the Constitutional Court for certification'," Motlanthe said.

His comments were made as the ANC in parliament showed signs of buckling under the pressure being brought to bear regarding the bill. ANC MPs yesterday said that they had made three crucial amendments to the bill.

The ANC has scrapped a clause that gave municipalities wide-ranging powers to classify information.

The ANC also dumped a clause that sought to criminalise the publication of information related to the functioning of security agencies such as the National Intelligence Agency.

Finally, it deleted a line that would have made the bill trump the Promotion of Access to Information Act. This sub-clause was widely branded as unconstitutional by organisations such as trade union federation Cosatu and NGO Freedom Under Law.

In a presentation to the multi-party ad hoc committee processing the bill in the National Council of Provinces, ANC MP Sam Mazosiwe described the proposed amendments as a "major leap forward".

"We are tabling an amendment that excludes municipalities [from classifying] documents.

"We are saying that this is a major leap forward [compared] to what we originally had. We believe [in taking] into account the views of the public and also the views of the committee in so far as making sure that our democracy prevails in all of our activities," said Mazosiwe.

But civil society group Right2Know was not satisfied with the proposed concessions, saying they were an inadequate response to fears that the bill was designed to prevent the media exposing corruption in the government.

Mazosiwe said the ANC had also decided to scrap the contentious section 49 of the bill, which sought to prohibit any disclosure or publication of matters relating to the National Intelligence Agency or other state security agencies.

Section 49 was criticised as an attempt to hide the activities of the state security apparatus.

"We are proposing that this proposal be deleted completely in the bill," Mazosiwe said.

But Alison Tilley, of Right2Know, said that though the deletion of section 49 was a "significant gain in terms of transparency" she was worried that the ANC was still not prepared to act on the calls for the inclusion of a public interest defence in the bill.

Opposition MPs said the proposed amendments were "a step in the right direction".

The amendments were agreed to in closed discussions between the ANC and a small group of MPs from the DA, COPE and the IFP.

The bill was passed by the National Assembly in November. Almost all the opposition MPs voted against the bill and a smattering of ANC MPs abstained.

The National Council of Provinces' ad hoc committee has until September 30 to report back to parliament before the bill can be finalised.