BEIJING (AP) - The World Health Organization says China must exert stronger oversight over vaccines sold on the private market in the wake of a scandal involving expired or improperly stored vaccines.

BEIJING (AP) The World Health Organization says China must exert stronger oversight over vaccines sold on the private market in the wake of a scandal involving expired or improperly stored vaccines.

Dr. Lance Rodewald of WHO China's immunization program said Tuesday that the ongoing investigation into what he called the "troubling" scandal that came to light last month would help identify ways to tighten regulation of the private market in vaccines.

Police say a woman and her daughter, who are both in detention, are thought to have sold nearly $100 million worth of the suspect products nationwide since 2011. More than 130 people have been questioned and 69 criminal cases filed in connection with the pair.

The scandal reinforces long-standing public concerns over the safety of China's food and medicine supply.