Former president Kgalema Motlanthe has told the BBC that he expected President Jacob Zuma to step down in 2016 after the Constitutional Court's ruling on non-security upgrades at his Nkandla home.

"It goes back more than a year ago when the Constitutional Court, which is the apex court of the land, said the president had failed to protect and defend and uphold the Constitution which is his obligation in terms of his oath of office.

"I thought the honourable thing for the president would have been to step aside," Motlanthe told BBC World Service Radio, which published the clip on Friday afternoon.

When asked whether he had made his thoughts known to Zuma, Motlanthe said he had made his views very clear and that African National Congress (ANC) parliamentarians were starting to see it as well.

"It doesn't make sense, even in Parliament: Honourable members of Parliament now say he is not an honourable person to head the State."

'Populism'

He also reportedly told the broadcaster that his vote for the ANC could not be taken as "given" come the 2019 elections.

Motlanthe also weighed in on Water and Sanitation Minister Nomvula Mokonyane's statement during an ANC Youth League rally in Ekurhuleni on April 4.

While hitting out at international rating agency S&P and its downgrade of South Africa's economy‚ Mokonyane said the world should respect the processes which made a government saying: "The west can't dictate to us. The rand falls. It fell in apartheid and we will pick it up again now."

Mokonyane was addressing a few hundred Zuma supporters six days after Motlanthe had read out excerpts from a letter written by struggle stalwart Ahmed Kathrada, during his funeral on March 29, in which the stalwart asked Zuma whether he would consider stepping down.

Two days after Kathrada's funeral Finance Minister Pravin Gordhan and his deputy Mcebisi Jonas were removed from their positions. On April 3, S&P announced that it had downgraded South Africa's credit rating to junk status.

In his interview with BBC, Motlanthe described Mokonyane's utterances "populism of the worst kind".

"If the minister can say the rand can fall; we'll just pick it up, that shows a cavalier attitude toward a very very serious matter.

"It's populism of the worst kind where people just want to issue statements that may resonate with poor people who have no understanding of the bigger issue so it's really disheartening," he said.