The WHO said it had sent an official "Notice of Concern" letter to Sandoz on September 12 after an inspection of the unit's Kempton Park factory in South Africa.
That had revealed 41 separate cases classified as "non-compliances and deviations from the WHO Good Manufacturing Practices."
For example, "the company failed to ensure that where starting and primary packaging materials and intermediate or bulk products were exposed to the environment, interior surfaces were not smooth and free from cracks and open joints, and did not permit easy and effective cleaning and, if necessary, disinfection," the WHO said in its letter.
The inspection was carried out in May, said the WHO.
Since then however, Sandoz had failed to take sufficient steps to remedy the situation and thus the WHO has deemed the Kempton Park site to be "operating not in compliance with WHO GMP."
As such, the WHO would "recommend suspension of procurement of all prequalified products manufactured at this site, (and) withhold prequalification of all new products," the letter said.
These recommendations would remain in force "until satisfactory corrective actions have been implemented by the manufacturer and verified by WHO," it added.