UPDATE 2-SAfrica union threatens to strike at Gold Fields

* Union says 45,000 workers could take part

* Company says confident talks will resolve dispute

(Adds Gold Fields statement)

JOHANNESBURG, Nov 11 (Reuters) - South Africa's biggest union said on Wednesday it had received the go-ahead from the authorities for its workers to strike at Gold Fields (GFIJ.J), over a disputed recruitment assessment method.

Gold Fields spokesman Julian Gwillim said so far no strike notice had been issued to the company, but that it was committed to finding a workable solution that satisfied both parties.

The National Union of Mineworkers (NUM) said some 45,000 workers across the world's fourth biggest producer of gold's operations in South Africa would go on strike unless the recruitment method was scrapped.

The union said the method acted as a barrier to new employees as well as staff coming back from maternity or annual leave, and wants the company to re-introduce an assessment method that was used previously.

The Commission for Conciliation, Mediation and Arbitration (CCMA) mediated the talks before they broke down, and granted the union a certificate to hold a strike.