South African postpones Zuma’s state of the nation address amid turmoil. [Photo:Courtesy]

South African President Jacob Zuma's state of the nation speech in parliament has been postponed, as pressure grows on him to resign.

Parliament speaker Baleka Mbete made the announcement, without giving a new date for the address that had been scheduled for Thursday.

The ruling ANC earlier called a meeting of the party's top body for Wednesday to decide the president's future.

Mr Zuma, 75, has resisted calls to quit over corruption allegations.

He was replaced as party leader by his deputy, Cyril Ramaphosa, 65, in December. He is now the front runner to succeed him as president.

Earlier on Tuesday, the Nelson Mandela Foundation urged Mr Zuma to step down.

South Africa had seen "systematic looting" under Mr Zuma's rule, and he "must go sooner rather than later", the foundation said in a statement.

In a statement, Ms Mbete said recent "calls for disruption" of a parliament meeting on Thursday "caused us great concern".

Therefore the decision had been taken, she said, to "create room for establishing a much more conducive political atmosphere in parliament".

She said that "with this in mind", Mr Zuma was approached about postponing the address, but "when we met the president, we then learnt that he was already writing to parliament to ask for the postponement".

Mr Zuma's office later said in a statement that "the president has requested the postponement due to certain developments".

South Africa's main opposition parties, the Democratic Alliance (DA) and the Economic Freedom Fighters (EFF), had been pushing for the postponement of Mr Zuma's speech.

They both welcomed Tuesday's announcement.