Johannesburg - Three former heads of state teamed up for the first time on Friday to conduct a series of dialogues around the state of the country under President Jacob Zuma, who faces growing calls to step down after a series of corruption scandals.

Thabo Mbeki, F.W. de Klerk and Kgalema Motlanthe spoke in Parktown, Johannesburg, representing both South Africa's last leader under white minority rule and those who led post-apartheid South Africa along with Nelson Mandela.

The country has seen tens of thousands protest against Zuma in recent weeks after he fired widely respected finance minister Pravin Gordhan, leading two credit ratings agencies to downgrade the country to junk status. The firing led some top leaders of the African National Congress to sharply criticize the president.

"No person or institution should have more authority than the will of the people," Mbeki said on Friday.

De Klerk, who shared the Nobel Peace Prize with Mandela for their work in transitioning South Africa from white minority rule, said Zuma has failed to uphold the country's laws.

The three leaders urged South Africans to defend the constitution as many in the country see threats to its democracy.

"The rose we planted in 1994 is indeed sick," Mbeki said, referring to the election that brought Mandela to power.

Calls have been mounting for Zuma to resign. South Africa's main opposition party, the Democratic Alliance, has called for a parliamentary vote of no confidence against him in the coming weeks.

Scandals around the president have included the spending of millions of rands in state funds on his private homestead at Nkandla. He paid back some of the money after the Constitutional Court ruled against him last year.

Associated Press