Johannesburg (CNN) -- South Africa's ruling party has suggested changes to controversial "state protection" legislation that critics say is a threat to press freedom and anti-corruption efforts.
Parliament's lower house voted for the legislation in November amid condemnation from groups vowing to challenge it in court.
The legislation -- called the Protection of State Information Bill -- makes obtaining, leaking or communicating classified state information punishable by up to 25 years in prison. It also allows federal and local officials to classify any document as secret.
Months after critics decried the legislation, African National Congress members of a committee in parliament's upper house Thursday suggested changes.
The proposed changes include allowing the publishing of classified information when "such a disclosure reveals criminal activity," the nation's SAPA news agency reported.
Under the changes, those charged with disclosure can argue in court that the information was wrongly classified, it said.
Another proposed change says a provision that criminalizes publishing state security information will apply only to classified information. Critics had said the legislation criminalizes the disclosure of information relating to any state security matter.
The African National Congress committee did not respond to CNN's repeated requests for comment, but it has said that the new bill is needed to update secrecy rules that have not changed since the apartheid era decades ago.
The legislation sparked condemnation and debates nationwide after the lower house vote, with critics decrying the harsh prison terms it calls for and its lack of a public interest defense clause.
While the proposed changes are a step in the right direction, they don't go far enough, said Nic Dawes, media freedom chairman of the South African National Editors' Forum.
"It seems clear that members of the committee have decided that the legislation must reflect the fact that the vast majority of those who made submissions on the bill called for a public interest defense to be inserted, along with other important changes," Editors' Forum Chairman Mondli Makhanya and Dawes said in a joint statement.
When the lower house voted for the bill, protesters dressed in black gathered in cities while newspaper headlines screamed "Black day for press freedom." The media declared the day "Black Tuesday" -- a reference to "Black Wednesday" in 1977 when the apartheid government banned two newspapers and several anti-apartheid groups.
The changes should not only protect journalists but citizens as well, said a spokesman for Congress of South African Trade Unions.
"The media is not our only concern -- we are also concerned about regular citizens and whistle-blowers who would find it more difficult to reveal information exposing corruption," said Patrick Craven, the spokesman. "We want an absolute guarantee that nobody is going to be prosecuted."
The ruling party committee has until June to debate the bill, which gives it more time to get it right, Dawes said.
CNN's Nkepile Mabuse contributed from Johannesburg and Faith Karimi from Atlanta