A South African army spokesman on Wednesday said it was awaiting instructions to either withdraw or increase the number of its troops in Central Africa after 13 soldiers died in a bloody battle for Banqui as rebels seized power.

Uncertainty surrounding the deployment emerged as President Jacob Zuma flew to Chad for regional talks on the crisis and amid public anger over the paratrooper's deaths.

Their killing by rebels has prompted allegations that the troops were deployed to protect commercial interests, and calls for an unknown number of troops remaining in the Central African Republic to be sent home.

Their deaths marked the country's heaviest military loss since the apartheid era.

Defence spokesman Brigadier General Xolani Mabanga said no decision had yet been made on soldiers still on the ground since Bangui fell just over a week ago.

"We are awaiting any instruction or guideline either to withdraw our forces and equipment that are in Central African Republic or to reinforce them," he told AFP.

"So at this stage there is no movement, there's nothing."

On Wednesday President Jacob Zuma flew to Chad for talks on Central Africa's post-coup crisis.

He had previously hit out at claims that the troops were sent to Central Africa to protect private business interests.

South Africa has explained its decision to send extra troops into Bangui this year as protection for troops already on a training mission as part of a 2007 pact.

But it also stated in 2011 that soldiers were deployed to provide VIP protection to fallen president Francois Bozize who fled his country after the capital fell.

Mabanga refused to comment on the "VIP protection unit."

Fresh outrage was sparked by Wednesday media reports claiming that troops and aircraft were being built up in the region.

The local media reports pointed to aircraft, including fighter planes, leaving for Uganda and the Democratic Republic of Congo. One suggestion was that this could be a strategic positioning ahead of the outcome of the Chad meeting.

Mabanga denied knowledge of a build up, however.

South Africa also has peacekeeping troops in DR Congo and Sudan's Darfur region.