Jacob Zuma was sworn in as South African president on Saturday after a remarkable political comeback and quickly highlighted the challenges faced by the continent's largest economy.

The prospect of the former guerrilla becoming the nation's fourth head of state since the end of apartheid was unthinkable when he was nearly ruined by graft and rape charges, crises that might have buried many politicians.

Promising to help South Africans realize their dreams, Zuma, 67, took a sober view of the country's economy which may already be in its first recession in 17 years.

'We must acknowledge that we find ourselves in difficult economic times. Jobs are being lost in every economy across the world,' the ANC leader said in his inauguration speech.

'We will not be spared the negative impact and are beginning to feel the pinch.'

Former president Nelson Mandela, like Zuma imprisoned on Robben Island under white rule, gave his seal of approval to the country's new leader by attending the ceremony.

Air force jets flew over the presidential offices where Zuma will have to make tough decisions after winning a strong mandate thanks to the ruling ANC's landslide poll victory on April 22.

ANC supporters in Zuma T-shirts, dresses and hats, danced in circles and shouted hymns. Some held up copies of newspaper headlines on placards which read 'Zoom. Zoom. Zuma.'

While South Africans respect the ANC for fighting white minority rule, which ended in 1994, they are growing impatient with rampant poverty, crime and an AIDS epidemic Zuma has promised to tackle.

'The needs of this country stare in your face, there is no way he could ignore what needs to be done,' said municipal government official Able Moshuhla.

One of Zuma's toughest tasks may be juggling the interests of the unions and communists who helped him rise to the top, with those of investors who fear he will steer the economy to the left.

Investors are especially interested in the fate of respected finance minister Trevor Manuel, praised for his fiscal management. Speaking to reporters before the swearing-in ceremony, Manuel expressed confidence in Zuma's abilities.

'Frequently people look for experience. But what matters is attitude and aptitude,' he said. 'The mood is very buoyed. Feeling very strong. There's a big wave to ride.'

Stacking the cabinet, to be named on Sunday, with loyalists could hurt the credibility of Zuma who has said ANC officials should not expect positions just because of their loyalty.-Reuters