Apparent progress in negotiations between South African mining unions and platinum producers Anglo American Platinum (Amplats), Impala Platinum (Implats) and Lonmin has been set back by new union demands.An 'in principle' agreement reached between the three platinum producers and Association of Mineworkers and Construction Union (AMCU) President Joseph Mathunjwa was mandated by the union's members, but in a letter to the trio the union introduced some new demands that seemed to dash renewed hopes of a resolution. A statement from the trio read that while the letter raised various procedural issues that the companies were willing to finalise with the union leadership, it also raised new hurdles. "Regrettably, however, the letters also contain new and additional demands which, if granted, would mean huge additional costs - of around 1bn rand in aggregate - to the companies, beyond the increases contained in the 'in principle' agreements."The companies said that they "simply cannot afford the additional wage demands" but that they remained engaged with AMCU on their latest demands and that large numbers of employees had returned to the platinum belt region, having spent the strike period elsewhere.OH