A South African court on Thursday further delayed a donation of military helicopters to Zimbabwe's army after the planned transfer sparked an outcry ahead of polls in the neighbouring nation.

The AfriForum lobby group, which brought the matter before the Pretoria court, said the court had upheld an earlier ruling blocking the delivery of spares and frames from South Africa's retired chopper fleet to Zimbabwe.

"The helicopters aren't going anywhere," AfriForum's Willie Spies said.

The French-developed Alouette III helicopter equipment is intended for the Zimbabwean Defence Force (ZDF), which critics allege backed President Robert Mugabe in previous bloody elections.

South Africa's defence department said the decision to give away the spares dated back to 1997. The helicopters were used -- including by apartheid forces -- from the early 1960s until 2007 when they were retired.

Zimbabwe is scheduled to hold elections this year -- though no date has yet been given -- to replace a shaky compromise government between Mugabe and long-time foe Morgan Tsvangirai.

The two were forced in the deal by regional powers, including South Africa, after election violence in 2008 killed around 200 people and caused an economic meltdown.

Critics including AfriForum fear Zimbabwe's army is enhancing its visibility and mobility ahead of the poll.

South Africa's main opposition Democratic Alliance has accused President Jacob Zuma's government of bordering on "state-sponsored smuggling" to help Zimbabwe's military get around international arms embargoes.

The equipment is set to be shifted without clearance under arms export regulations, which stipulate no trade with aggressive or repressive states, as it reportedly had been stripped of all weapons systems.

The European Union and the United States imposed a visa ban and assets freeze on Mugabe and his inner circle, as well as an arms embargo on the country, following disputed presidential polls in 2002.

United Nations sanctions against Zimbabwe, including an arms embargo, were vetoed in 2008.

Under the power sharing deal with Tsvangirai, Mugabe has retained control of the army and police. Both forces are seen as highly loyal to the 89-year-old veteran leader.