Iraqiya state television broadcast his statements at the weekend but they were made in court last Wednesday, said Mohammad Abdul Sahab, spokesman for the special court which rules on Saddam-era crimes.
"I speak here of the history of Iraq. There was an oppressor and the oppressed during the old regime. Now that Saddam is gone, I can speak freely," Watban said of his half-brother who was executed in December 2006.
"This is the only platform where I can make my voice heard to the Iraqis. I must apologise to the great Iraqi people for what it was subjected to under the Baath party," he said, becoming the first official from Saddam's inner circle to offer a public apology.
"The party behaved as if it had the absolute right to lead the country. The party leadership dealt with the soul and money of Iraqis as if it had an absolute right to do with them as it wished."
Watban was seriously wounded in 1995 when Saddam's elder son, Uday, fired nine bullets into his leg.
Arrested on April 13, 2003 by the US-led coalition which invaded Iraq as he tried to flee to Syria, Watban was sentenced to death in March 2009 for his role in the 1992 executions of 42 traders accused of price fixing.
Turning in court to Aziz, who was sentenced to death last October, he accused the former deputy prime minister of having been "the architect of the policies of the Baath party."
The half-brother said he had seen Saddam two days before his execution and asked him to dissolve the party, which ruled Iraq from 1968 until the invasion.
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