(AFP) - South Africa will learn Monday if a parliamentary vote of no confidence in President Jacob Zuma will be by secret ballot, a move that could encourage ANC lawmakers to oust him.

Tuesday's vote has become a test of African National Congress (ANC) unity as senior party figures have been increasingly critical of their leader, but it is unlikely to succeed in toppling Zuma.

The president, who came to power in 2009, has been implicated in multiple corruption scandals, while the country's economy has fallen into recession and unemployment has risen to record levels.

The 75-year-old is due to step down as head of the ANC in December, and as president before the 2019 general election -- lessening pressure for his party to seek imminent change.

Parliamentary Speaker Baleka Mbete is due to announce on Monday at 3:30pm (1330 GMT) whether the vote will be held in secret as requested by opposition parties.

The ruling has been subject to a long legal battle, and the vote on Tuesday evening could still be delayed by further court appeals.

Protests by pro- and anti-Zuma groups are planned in Cape Town, home of the South African parliament, on Monday and Tuesday.

The main opposition Democratic Alliance party said the vote was "an opportunity for us all to stand up to corruption and get rid of President Zuma and his cabinet."

A group of ANC veterans from the anti-apartheid struggle also called for lawmakers to vote against Zuma, who was himself imprisoned with Nelson Mandela on Robben Island under white-minority rule.

South Africa is "witness to larceny on a grand scale, leaving the country not only impoverished, but also increasingly in the hands of criminalised and compromised governance," the veterans said in a statement ahead of the vote.

The ANC has fought back, saying it expects its lawmakers to back the president.

Party chief whip Jackson Mthembu said ousting Zuma would "have disastrous consequences that can only have a negative impact on the people of South Africa".

But he acknowledged recent criticism of the ANC, and the impact of a cabinet reshuffle in March when respected finance minister Pravin Gordhan was replaced with a Zuma loyalist.

Gordhan's sacking led to a string of downgrades to South Africa's credit rating as well as causing the rand currency to tumble.

Public support for the ANC, which swept to power under Mandela in the first non-racial elections in 1994, slipped to 55 percent in last year's local polls -- its worst-ever election result.

But Zuma has easily survived several previous parliamentary votes attempting to oust him, due to the ANC holding 249 seats in the 400-seat parliament.

© Agence France-Presse