Johannesburg - MTN plans to lay off around 850 managerial staff, a union official said on Monday, 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 Vodacom.

“We have just received a massive retrenchment notice at MTN,” said Marius Croucamp, a spokesman at the Solidarity Union, which largely represents skilled workers.

MTN's revenue from South Africa fell by 7 percent to 19.2 billion rand 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 percent at 12:46 SA time. - Reuters