Sanofi's plan to restructure its research operations in France could lead to more job losses than the 900 layoffs mooted by the drugmaker, union representatives said.

Unions said the company's figure underestimated the number of job cuts as Sanofi reshuffles its laboratories into regional research hubs at the expense of smaller centers.

"There are thousands of employees that will be hit by layoffs and a high number of internal transfers," Pascal Vially, a representative for the CFDT trade union, told Reuters.

Sanofi has scaled back planned layoffs under pressure from the French government, which has been struggling to contain a rising unemployment rate, and said it could shed around 900 jobs in France in the next three years - fewer than the 2,500 predicted by trade unions.

But the 900 cuts - to be achieved through voluntary redundancies, internal transfers and early retirements - do not include the 640 jobs at a cancer research centre in Toulouse, which Sanofi wants to exit.

The unions will discuss Sanofi's plan with Industry Minister Arnaud Montebourg at a meeting on October 12, a day after the company is due to provide details of the cuts.

Montebourg sided with the unions in a TV interview last week, saying the scaled-back plan is "still too much.

Neither Montebourg's office nor Sanofi were immediately available for comment.

(Reporting by Noelle Mennella; Writing by Elena Berton; Editing by David Holmes)