The May 17 deadline for MPs to finalise the contentious Protection of State Information Bill may again be postponed.

Raseriti Tau, the chairman of the National Council of Provinces committee working on the bill, on Friday urged members to isolate the main arguments raised in recent provincial and parliamentary hearings on the draft act, saying this should allow them to conclude their deliberations in June.

Tau later scrambled back when asked about shifting the deadline for reporting to Parliament on the bill.

"I don't want to talk about extensions. We are trying our best to work within the limited timeframe," he told the media.

Tau also refused to comment on the possibility of amending the bill, though it is reliably understood that at least some changes are on the cards.

This would see the bill sent back to the National Assembly to approve those amendments before it could be signed by President Jacob Zuma.

Democratic Alliance MP Alf Lees said the deadline had to be moved back to allow the committee to right serious problems that remain with the bill.

"I have that no doubt that we will go on after May 17."

The committee on Friday convened to accept a report summarising the overwhelmingly critical commentary on the so-called "secrecy bill" from the hearings.

Alison Tilley, from the Open Democracy Advice Centre, said it was heartening that the committee had taken the trouble to compile the input and planned to mull it in deliberations next week.

Over four days of hearings in Parliament in late March, veteran human rights lawyer George Bizos led a chorus of warnings that the bill was unconstitutional. Cosatu general secretary Zwelinzima Vavi vowed to be the first to launch a legal challenge unless it were redrafted. Vavi said the bill would take South Africa back to being a security state, a concern that has been amplified by the wide powers given to controversial crime intelligence boss Richard Mdluli.

Like Bizos, Vavi called for a public interest defence to be written into the legislation to protect whistleblowers and journalists who risked long prison sentences for disclosing state secrets that cover up corruption.

Public Protector Thuli Madonsela told lawmakers the bill, if it were passed, would derail her work and undermine more progressive information laws.

This week Nobel literature laureate Nadine Gordimer took the debate abroad when she told the New York Times Review of Books the legislation was a threat to freedom of expression and should be rejected in its entirety.