(AFP) - South African President Jacob Zuma prepared to deliver his annual state of the nation address on Thursday after deploying more than 440 soldiers to prevent a repeat of violent clashes outside parliament.

Zuma, 74, has faced growing criticism since his last address over a series of damaging corruption scandals, worsening unemployment levels and slowing economic growth.

In December, he beat back an attempt by at least four ministers to oust him from power, following local elections that delivered the ruling African National Congress (ANC) party's worst-ever results.

The president said the military deployment was to maintain "law and order" outside parliament in Cape Town, but the move was condemned by the main opposition Democratic Alliance party.

"The DA will not stand by and allow for the 'people's parliament' to be turned into a security-state show of force, meant to intimidate opposition both inside and outside of the ANC," it said in a statement.

Zuma's state of the nation address has been hit by regular protests in recent years.

In 2016, lawmakers from the leftist Economic Freedom Fighters (EFF) -- dressed in their uniform of red workers' overalls and hard hats -- noisily interrupted his speech before eventually being ordered out of the chamber.

Outside on the streets of Cape Town, police fired stun grenades to disperse angry protesters.

The city, a stronghold of the DA party, has been under a tight security clampdown this week.

The 2015 state of the nation address degenerated into chaos as protesting EFF lawmakers were violently evicted by bouncers.

The EFF, led by firebrand Julius Malema, has not said whether it will try to shout Zuma down this year, but it described the use of soldiers as a "declaration of war on citizens".

- Zuma heads to exit -

Zuma is set to step down as leader of the ANC in December, before the general election in 2019 that will mark the end of his two-term reign as national president.

South Africa, the continent's most industrialised economy, expanded by about 0.4 percent last year.

Inflation hit 6.8 percent in December and unemployment has risen to a 13-year high of 27 percent.

"The party is more unsure of itself, they appear overly paranoid," Daniel Silke, an independent political analyst, told AFP.

"Deploying the military shows the increasing frustration within ANC after the last two years of disruptions."

Zuma, a traditionalist leader who came to power in 2009, is widely seen as being at loggerheads with Finance Minister Pravin Gordhan, a reformist respected among international investors.

South Africa's highest court last year found the president guilty of violating the constitution after he refused to repay taxpayers' money used to refurbish his private rural house.

He is also fighting a court order that could reinstate almost 800 corruption charges against him over a multi-billion dollar arms deal in the 1990s.

A separate probe by the country's top watchdog uncovered evidence of possible criminal activity in his relationship with the Guptas, a business family accused of wielding undue political influence.

Increasing numbers of anti-apartheid veterans, ANC activists, trade unions, civil groups and business leaders have called for Zuma to resign.

"You must know that as a nation we no longer have confidence in your leadership," Sipho Mila Pityana, leader of the Save SA action group, said on the eve of Zuma's speech, which is scheduled to start at 1700 GMT.

"You are not trusted by the people. You are not trusted by civil society. And, increasingly, you are not even trusted by your own party and its allies."

However Zuma retains strong loyalty among many rank-and-file ANC party members and its lawmakers.

© Agence France-Presse