CAPE TOWN — Cyril Ramaphosa has become South Africa's president a day after embattled leader Jacob Zuma resigned.

He was the only candidate nominated by parliament, which is dominated by his African National Congress. MPs broke into song at the announcement.

In his first presidential speech, Ramaphosa, 65, said he would tackle the corruption which allegedly became widespread under Zuma.

The ANC had told Zuma to step down or face a vote of no-confidence.

Zuma faces numerous corruption allegations but denies any wrongdoing.

One allegation is that he allowed the wealthy Gupta family, who whom he has personal ties, to wield influence over policy, in an example of "state capture".

An arrest warrant has been issued for Ajay Gupta, one of the three most prominent Gupta brothers, officials said on Thursday.

This follows a raid by the Hawks, an elite police unit, on their home on Wednesday. The family has denied corruption allegations.

President Ramaphosa told parliament that corruption and state capture were "on our radar screen".

He is due to deliver a State of the Nation address on Friday. This was delayed last week amid uncertainty about who should deliver it and Zuma's reluctance to step down.

One opposition party, the Economic Freedom Fighters, walked out of the parliamentary debate. It wants new elections, rather than the ANC deciding on the identity of the new president.

Ramaphosa is likely to seek to boost foreign investment partly through reforms to regulations controlling ownership of the mining sector, a key national industry.

The struggle to create jobs is hampered by an economy that grew just 1.6 percent a year under Zuma. Analyst say more than five percent a year is required to reverse the unemployment crisis.

Drought, low commodity prices and weak demand for exports have all taken their toll, as well as government graft and policy missteps under ousted president Jacob Zuma.

The World Bank predicts just 1.1 percent growth in 2019 — below the country's population growth rate and therefore increasing poverty per capita.

Low growth has also increased the budget deficit. The nation's debt was last year downgraded to junk status by the Standard & Poor's and Fitch ratings agencies.

Uprooting South Africa's widespread culture of graft will be a years-long challenge, for patronage networks are embedded deep in politics and business.

Ramaphosa starts his administration with a government that includes Zuma's closest allies, some of whom are accused of corruption. A major clearout may be expected in the coming weeks.

As deputy president, Ramaphosa had to fight a bruising battle to secure the top job. First he had to become head of the ruling ANC party, defeating Zuma's chosen successor in a fierce and closely-fought election in December, and then chart a strategy for forcing out his boss.

The fight exposed deep divisions in the party ahead of a general election in 2019 and intensified the fall in the popularity of the ruling African National Congress (ANC) party.

Uniting the ANC and organizing a successful election campaign will be priorities for Ramaphosa, even though the ANC still has the advantage of a large majority in parliament.

The 54 percent of the vote that the ANC won in 2016 local elections was the party's worst result since it came to power in the 1994.

The party faces threats from the centre-right Democratic Alliance and the leftist Economic Freedom Fighters parties. — Agencies