Tens of thousands of people marched through South African cities on Friday in largely peaceful protests to demand President Jacob Zuma's resignation.

In the biggest political protests in years, large crowds gathered in the capital Pretoria, the economic hub Johannesburg, and the coastal cities of Durban and Cape Town.

Nobel laureate and anti-apartheid leader Desmond Tutu, 85 and frail in health, made a rare public appearance to support the protests outside Cape Town.

Several thousand people attended the Johannesburg protest organised by the opposition Democratic Alliance party, which hopes to make gains in the 2019 elections.

"We want Zuma to fall. He is too corrupt. Real people are struggling," protester Vanessa Michael, 54, told AFP news agency.

Mabefw Malega, a 38-year-old undertaker who had travelled three hours from Limpopo province to march, said: "People just want Zuma gone".

Al Jazeera's Fahmida Miller, reporting from Pretoria, said the demonstrations are significant because "it's just the beginning of protests and marches by a large sector of South Africans calling for the president to resign".

She added that protesters say there are more demonstrations to come.

While Friday's marches remained largely peaceful, groups of protesters scuffled outside the Johannesburg family mansion of the wealthy Gupta family.

The relationship between Zuma and the Guptas has been an issue for years, amid allegations they have undue influence on the president. Both families have denied any wrongdoing.

Zuma's sacking of respected finance minister Pravin Gordhan last week has fanned public anger, divisions within the ruling African National Congress (ANC) party, and a sharp decline in investor confidence in the country. 

OPINION: Even if Zuma goes, South Africa will remain divided

Zuma, who came to power in 2009, has been battered by a series of corruption scandals during his time in office, while the country has suffered record unemployment, slowing growth and stubborn racial inequality. 

His removal of Gordhan unleashed a fresh bout of criticism, as many South Africans and international investors saw the former minister as someone who fought corruption.

The demonstrations came as a second ratings agency downgraded the country's debt to junk status.

"Recent political events, including a major cabinet reshuffle, will weaken standards of governance and public finances," the Fitch ratings agency predicted as it announced the downgrade. 

Earlier this week, the Standard & Poor's agency downgraded the South African sovereign debt to "junk" status after Zuma's dramatic ministerial shake-up.

ANC backs Zuma

Zuma supporters also gathered outside the ANC headquarters in Johannesburg on Friday and the ANC Youth League held a counter-protest in Durban. 

The ANC led the decades-long struggle against apartheid, and carried Nelson Mandela to power in the 1994 elections that ended white-minority rule.

But the party has lost popularity in recent years and slipped to 55 percent of the vote in last year's local elections - its worst ever result.

Zuma this week appeared to have quelled a rebellion within the ANC despite senior party figures, including Deputy President Cyril Ramaphosa, speaking out against Gordhan's sacking.

READ MORE: South Africa's ANC stands by President Jacob Zuma

On Wednesday, the ANC acknowledged, but rejected calls for Zuma to step down. 

ANC secretary-general Gwede Mantashe told reporters that although the party had "reflected" on the resignation demands, "we won't recall President Jacob Zuma because opposition parties say so. It won't work that way."

Zuma, 74, is due to step down as head of the ANC in December, and as president ahead of the 2019 general election.

Parliament will vote on a motion of no confidence in the president on April 18, though Zuma has easily survived such votes against him before.

INSIDE STORY: What's behind South African finance minister's sacking?

Source: Al Jazeera and news agencies