This is as the mobile operator faces slowing growth and tough competition in its home market.
Africa's largest telecommunications group has expanded rapidly in the last two decades across the continent and in the Middle East but is facing stiff competition in South Africa, where the market is dominated by rival [DATA VOD:Vodacom].
"We have just received a massive retrenchment notice at [DATA MTN:MTN Group]," said Marius Croucamp, a spokesman at the Solidarity Union, which largely represents skilled workers.
(READ MORE: MTN makes key leadership changes)
MTN's revenue from South Africa fell by 7 per cent to 19.2 billion rand ($1.8 billion) in the first half of this year while its margins also declined.
An MTN spokeswoman said it would be issuing a statement shortly. Its shares were down 1.8 per cent at 10:46GMT.