The National Union of Mineworkers's (NUM's) leaders have voted to go on strike at Eskom from next week.

"They've taken a decision to go on strike. They will mobilise [Wednesday] and go on strike from next week," spokesperson Lesiba Seshoka said on Tuesday.

The decision was taken despite the possibility that industrial action may be illegal.

"I don't know what to say about that. What I can say is that the council has voted to take this decision and will cross that bridge when they come to that. On any other issue, whether it is legal matters, they will cross that bridge when they come to it."

Eskom human resources managing director Bhabhalazi Bulungu said that the public utility was waiting for formal communication from NUM and was still holding out hope of meeting the union on Wednesday.

Eskom would continue to seek dialogue while trying to prevent a strike.

"There are many options we can do. We can go to court again for an interdict.

"We will continue to talk to them. We will talk to the highest leadership in the [Eskom] board. We will go to the chairperson of the board. We talk to the minister [of public enterprises]." If the NUM did strike, Bulungu said that Eskom would be prepared.

"We will take measures to ensure the security of the supply."

Negotiations between NUM and Eskom have broken down over demands of a wage increase and housing allowance.

Seshoka said that Eskom's most recent offer was for an 8,5% increase and a R1 000 housing allowance.

Unions had been insisting on a 9% increase and a R2 500 housing allowance. Seshoka said that the NUM would have been willing to compromise on the wage increase if management had acceded to their housing allowance demand.

"They've rejected the 8,5% and the R1 000 housing allowances. If you want 8,5% then the housing allowance has to be R2 500."

Bulungu said earlier that Eskom was planning meetings with the public utility's other unions, Solidarity and the National Union of Metalworkers, on Wednesday.

They would also try and get a meeting with the NUM.

Seshoka dismissed this possibility. "I don't see how they can at this point meet [on Wednesday]."