The decision to grant special remission of sentence to certain offenders was necessary, ANC chief whip Mathole Motshekga said on Monday.
"This exercise will therefore significantly reduce overcrowding and bolster the impact and effectiveness of rehabilitation programmes on serving inmates," Motshekga said in a statement.
"We call on all recipients of this presidential remission to take full advantage of this opportunity and become useful and better members of the society."
President Jacob Zuma announced on Friday, Freedom Day, that his administration would grant the special remission to specific categories of sentenced offenders, probationers and parolees.
According to weekend reports former police commissioner Jackie Selebi and Zuma's former financial adviser, Schabir Shaik, would benefit from the decision.
In 2005, the Durban High Court sentenced Shaik to 15 years in prison for fraud and corruption. In March 2009, after serving two years and four months of his sentence, Shaik was released on medical parole after being diagnosed with a terminal illness.
Selebi was convicted of corruption on July 2, 2010, and handed a 15-year sentence.
Police Minister Nathi Mthethwa said more than 35,000 offenders could be released, depending on an assessment.
Motshekga said constitutional prerogative had been exercised by various presidents since 1994 to mark special occasions.
Those sentenced for aggressive, sexual, firearm and drug-related offences, as well as escapees, would not qualify for early release.