Eskom has warned that a strike could put more pressure on its ailing electricity supply system.

Members of the National Union of Metalworkers are threatening to strike after wage negotiations broke down on Thursday.

Eskom says the strike will be illegal, as its employees are categorised as essential services staff and barred from embarking on industrial action. Unions are demanding a 15% salary increase while the company is offering nothing.

Eskom’s spokesperson Khulu Phasiwe says the security of supply could be undermined by a strike.

“If we do have any occurrences at our power station at this stage it will put the whole system under strain, because winter generally is a period where SA uses lot of electricity, and therefore all our machines to be running without any hindrances. All of these things are coming at a time when six of our power stations do not have enough coal, so you don’t want another added dimension on the issues we are already dealing with,” says Phasiwe.