Opposition parties and civil society groups have reacted with anger after the National Assembly on Tuesday passed the controversial Protection of State Information Bill, also known as the "secrecy bill".

Parliament's public and press galleries as well as the opposition benches were filled with people dressed in black for what had been dubbed "Black Tuesday" by those who saw the bill as a blot on South Africa's democracy.

Several political parties, many NGOs, the anti-bill lobby group Right2Know and the South African National Editors' Forum had voiced their opposition to the bill being passed without a public-interest defence clause that would allow the media to report on matters it deemed of public importance.

Joe Mcgluwa, Independent Democrats MP, said it was a sad day for all South Africans.

"We acknowledge that good changes have been made in comparison to its original version. We are, however convinced that many sections of the bill may be unconstitutional," he said, adding that the bill would not only affect the media, but also MPs who wanted to uncover corruption in the government.

"This is a people's Parliament - elected by the people. Why should we keep secrets from the people while the African National Congress promised transparency during the apartheid days?" Mr Mcgluwa said.

The bill still has to be approved by the National Council of Provinces next year.

Pieter Mulder, leader of the Freedom Front Plus, said: "Which country in Africa has the strongest opposition in terms of numbers? The answer: Zimbabwe. But without whistleblowers and with comprehensive limitations on the media, the Zimbabwean opposition is paralysed when it comes to exposing corruption. With this legislation we are regressing in this direction."

During the National Assembly session, Steve Swart, African Christian Democratic Party MP, told lawmakers that it was "ludicrous to compel a journalist who is leaked classified information that exposes state fraud or corruption, or even an imminent danger to public safety, to first surrender that document to the local police station before applying for declassification or approaching a court of law".

Mr Swart added: "The mere delivery of that classified document to the police will no doubt result in the arrest of such journalists or at least a police investigation into that journalist's source.

"This will result in the 'chilling effect' on press freedom in the country, referred to by various commentators on the bill."

Lindiwe Mazibuko, parliamentary leader of the Democratic Alliance, told the National Assembly: "It should never have come to this. Today is a dark day for our young democracy. If passed, this Bill will unstitch the very fabric of our constitution. It will criminalise the freedoms that so many of our people fought for."

Media Monitoring Africa, the journalism watchdog and campaigner for human rights, said it noted "with deep regret" the decision taken in the National Assembly to pass the bill, and called on President Jacob Zuma to send it back for revision.

"A side effect of the bill is that it has seen a trend towards national, provincial and local institutions tending towards a culture of secrecy," the organisation said.

"Several of the citizen protests that have taken place have been about people in poor communities demanding not only responses from local councillors but also information from their municipality. Each time the bill is endorsed by national figures, the culture of secrecy is deepened."

The Helen Suzman Foundation also condemned the passing of the bill, saying it marked a low point in South Africa's transition to democracy.

"The South African constitution enshrines and protects the free flow of information between citizens, and from our government to our citizens," it said. "This access to information is essential for accountable, transparent and responsive government. It is an essential component of the liberal constitutional democracy which South Africa aspires to be."

The foundation added that the bill could not credibly be described as in the country's best interests. "Instead, it is a case of political expediency triumphing over constitutional rights. It marks the beginning of policy being driven by a secretive and self-serving security cluster."