JOHANNESBURG - South African workers striking over pay and benefits have a new complaint - they no longer have the energy for sex.

Monroe Mkalipi, a regional chairman of the powerful COSATU federations of trade unions, complained that work conditions are so tough workers can't perform in the bedroom.

"The harshness that we have in all our workplaces is so severe to such a point that when you get home at night it becomes a problem expanding our families," the SAPA news agency quoted him as saying.

Public sector workers are negotiating with the government to increase pay for the first time since 2004.