Unions representing about three-quarters of workers at South Africa's state-owned power company Eskom have threatened to call a strike over pay.
The move could potentially disrupt electricity supply during the World Cup football tournament, currently being hosted in the African nation.
The National Union of Mineworkers (NUM) and the National Union of Metalworkers of South Africa (NUMSA) warned of a strike if Eskom failed to meet their demands by today.
Eskom has said that should the action go ahead, it will implement contingency measures to minimise the impact, reports Reuters.
The NUM, which represents about half of the 32,000 workers at Eskom, lowered its pay rise demands from more than three times the inflation rate of 4.6 to 9%. The unions also want the introduction of a housing allowance.
Eskom has offered an 8% raise and a one-off payment for housing.
South African workers have issued a series of threats to freeze transport, abandon security posts and tie up immigration at airports during the World Cup, which runs until 11 July, if demands for better wages and working conditions are not met.
Apart from some transport disruption, such action has so far largely failed to materialise, writes Reuters.