South Africa President Cyril Ramaphosa has described the corruption that has engulfed the country in recent years as "an amoeba" with "tentacles all over".
But he insisted South Africa's "very dark period" under his predecessor, Jacob Zuma, was coming to an end.
Mr Ramaphosa confirmed he would give evidence in a judge-led inquiry into allegations that top officials looted from the state on a grand scale.
Mr Ramaphosa served as then-President Zuma's deputy.
Mr Zuma was charged last April with fraud and racketeering linked to a 1999 arms deal. Much of his nine-year tenure as president was dogged by corruption allegations, while the country struggled with ballooning national debt and high levels of unemployment.
President Ramaphosa is not prone to dramatic outbursts, but at a news conference he launched an extraordinary attack on the corruption that has engulfed the country, reports the BBC's Andrew Harding who was there.
He acknowledged that South Africans were angry and needed to see senior government officials tried and sent to prison. He even compared the current situation to a rape victim forced to watch her attacker go unpunished, our correspondent notes.
An official inquiry is being held to investigate the claims of what is known in South Africa as "state capture", and Mr Ramaphosa confirmed he would appear before it.
"I will give an account to the commission about what I knew and what I didn't know," he said.
He spoke of his hope that South Africans would regain trust in the ruling African National Congress (ANC) - the party that has governed South Africa since Nelson Mandela led it to power after apartheid ended in 1994.
"The shine that had been tarnished is coming back and people are realising this. We are in a new period now - we are no longer in a period where we were just sliding downwards," Mr Ramaphosa said.
"Many people are looking anew at the ANC. They have a sense that we are now beginning to deal with corruption."