JOHANNESBURG - Large parts of Johannesburg were without electricity on Thursday -- including the suburb where a critically ill Nelson Mandela is recuperating -- due to a strike that could see blackouts for days.
Johannesburg City Power, the company providing electricity to South Africa's economic hub, said it had restored power to several areas but warned that the outages could last for up to three days.
"It could be anything between now and the three next days," spokesman Hloni Motloung told AFP.
Additional security had been put in place after the electricity supply was suspected to have been physically switched off at affected sub stations.
"We've involved the police in terms of investigating who is sabotaging our network," said Motloung.
Security guards had been deployed to "guard our sub stations, he added.
Around 200 technicians downed tools on Wednesday afternoon, refusing to work outside normal working hours, Sapa news agency reported.
The suburb of Houghton, home to former president Mandela's residence, was also affected.
The anti-apartheid icon, 95, is recuperating at his home which has been reconfigured so that he could receive intensive care, following his release from nearly three months in hospital on Sunday.
City Power installed a back-up generator to feed electricity to Mandela's house "mainly because of his health", said Motloung.
Another generator could be heard from outside its high walls, according to Sapa.
At the start of September, Johannesburg City Power introduced evening shifts in an effort to decrease power outages in Africa's largest economy, which has been facing electricity shortages for years.
A court order issued early on Thursday had ordered the technicians back to work, but so far they have not done so.
Power cuts in the city's western and northern parts caused traffic delays, according to police.
The strike occurs in a tense labour environment, with mass wage stoppages across the country.