Former president Zuma was forced out of office in 2018 under a cloud of corruption allegations
Former president Zuma was forced out of office in 2018 under a cloud of corruption allegations AFP

South Africa's electoral officials said on Thursday they had excluded former president Jacob Zuma from May elections, further increasing tensions in the run-up to the polls.

The country is to hold general elections on May 29 in what is expected to be the most competitive vote since the advent of democracy in 1994.

The ruling African National Congress (ANC) is on the brink of dropping below 50 percent of the vote for the first time since it came to power at the end of apartheid.

The party that has been in power for three decades is bleeding support amid a weak economy and allegations of corruption and mismanagement.

Zuma, 81, was forced out of office in 2018 under a cloud of corruption allegations but still wields political clout.

He has been campaigning for the opposition uMkhonto we Sizwe (MK) party in an attempt to relaunch his career and weaken his former party, the ANC.

"In the case of former president Zuma, yes, we did receive an objection, which has been upheld," electoral commission president Mosotho Moepya told reporters, without giving details.

"The party that has nominated him has been informed" as have those objecting to the move, he added.

The decision can be appealed before April 2.

MK spokesman Nhlamulo Ndlhela told AFP the party was "looking at the merit of that objection but we will of course will appeal it".

The general election, after which the victor will appoint a president, is set to be tense.

If the ANC falls below 50 percent of the vote it would force the party once led by Nelson Mandela to form a coalition to stay in office.

Latest polls put the ANC on just over 40 percent of the vote with the main opposition Democratic Alliance on around 27 percent and 13 percent for the MK.

The electoral commission said in a statement that under the constitution "any person who was convicted of an offence and sentenced to more than 12 months imprisonment without the option of a fine" cannot stand in an election.

Zuma was sentenced to 15 months in jail in June 2021 after refusing to testify to a panel probing financial corruption and cronyism under his presidency.

He was freed on medical parole just two months into his term.

But his jailing sparked protests, riots and looting that left more than 350 dead in South Africa's worst violence since the advent of democracy.

An appeals court later ruled Zuma's release was illegally granted and ordered him back to jail.

But on returning to a correctional centre he immediately benefited from a remission of non-violent offenders approved by his arch-rival and successor President Cyril Ramaphosa.

Besides his 2021 contempt conviction he is facing separate charges of corruption in an arms procurement scandal in the 1990s, when he was vice president.

Zuma cannot in theory seek re-election as he has already served two terms as president.

Final electoral lists are due to be published within around a fortnight.

The electoral commission has received 82 appeals relating to candidates designated by 21 political parties.

Zuma's declaration in December that he would campaign for the MK was a blow for the ANC.

The announcement of his exclusion came as the head of the Democratic Alliance John Steenhuisen refused to rule out a coalition deal with the ANC after the elections.