South Africa might need to consider introducing subjects related to ethics in schools to curb the scourge of corruption and make people understand the "devastation" it caused, Deputy President Kgalema Motlanthe said last night.

Motlanthe, speaking at the annual Ruth First Memorial Lecture at the University of the Witwatersrand, said corruption was "cancerous".

"The pestilence of corruption menacing the soul of our democracy is a life-and-death matter on which our future depends."

He said corruption "ultimately chokes off key societal institutions" and that everyone, including political leaders, needed to work together to eliminate it.

Motlanthe said corruption was the second "most serious malady staring humanity in the face" after racism. He said effective laws alone could not win the war against corruption.

Ultimately the "fight against corruption boils down to the individual's sense of right and wrong".

"We may need to begin exploring creative ways of introducing subjects related to ethics into our school curriculum very early in the development of the learner."

Last night's lecture marked the 29th anniversary of the death of Ruth First, the anti-apartheid activist who was killed by a letter bomb in Mozambique in 1982.

Without referring directly to the Protection of Information Bill, Motlanthe said the country must commit to never betray First's vision of "a South Africa where freedom of expression is as essential as the air we breathe".

He also said the government should be willing to accept criticism by patriotic South Africans.

"No government is perfect; mistakes will always happen.

"Accepting criticism and conceding to our errors without imputing evil motives to those committed South Africans who point out our mistakes with the best interests of our nation at heart should be as normal as voting for any party we choose," Motlanthe said.