The South African parliament has passed a bill aimed at protecting state secrets that opponents say will stifle the media and those who expose corruption.

Lawmakers adopted the bill by a vote of 229 to 107 Tuesday, with much of the support coming from the ruling African National Congress party.

The legislation prohibits the release of classified documents, even if the information contains details that could benefit the public. Those who publish classified information could face up to 25 years in jail.

Critics of the bill held protests Tuesday at ANC headquarters, wearing black to show their opposition – a reference to a 1970s apartheid-era press crackdown.

Opponents of the bill include Nobel laureate Desmond Tutu, who said the the law is “insulting” to South Africans, and that it would effectively outlaw whistle-blowing and investigative journalism.

The head of Zimbabwe's union of Journalists, Foster Dongozi, said the ANC is following the path of President Robert Mugabe's ZANU-PF party, which passed a similar law to silence critics.

ANC Secretary General Gwede Mantashe told VOA that South Africa's ruling party has a duty to protect national security information.