South Africa's National Union of Metal Workers (NUMSA) is taking the local arm of General Motors (GMSA) to court over job losses it says are linked to the parent company's financial woes, the union said on Thursday.

NUMSA also threatened to strike at GMSA when the economy recovers, and warned other car companies over job cuts.

The automotive industry approached the South African government for short-term loans in February, to help limit job losses.

The National Association of Automobile Manufacturers said more than 20,000 jobs were on the line due to falling local sales and declining exports on the back of the global economic downturn.

NUMSA said General Motors had retrenched and offered separation packages to over 1,300 workers since 2007.

NUMSA is demanding that GMSA must reinstate all the workers that it wrongfully retrenched ... place a moratorium on retrenchments and consult in good faith so alternatives to retrenchments can be adopted.

Reasonably, we are starting in the Labour Court of Johannesburg today ... to seek relief.

GM South Africa said on June 1 it would not be affected by its parent company's bankruptcy filing. The 100-year-old General Motors Corp (GM.N) filed for bankruptcy last week.

NUMSA said the failure of the parent company had led to the shutdown of production of the Hummer, worsening job losses.