Guangxi Yingkang Pharmaceutical Co, which is based in the Guangxi Zhuang autonomous region, said on Wednesday it suspended sales of a type of vitamin C tablets and sealed the products in storage, the Beijing Times reported on Thursday.

The move comes after media reports said that some of the pills were made with fake materials or materials contaminated with toxic chemicals, the report said.

The company is a unit of Guangzhou Pharmaceutical Holdings, which is based in Guangdong province.

A major material for the Vitamin C Yinqiao tablets made by Guangxi Yingkang Pharmaceutical — wild honeysuckle flowers — were sprayed with industrial sulfur by farmers before being sold to the company to prevent it from rotting in storage, the report added.

The wild honeysuckle flowers may contain an excessive amount of toxic substances such as mercury and arsenic after it was sprayed with the sulfur, it added.

It was also reported that some of the tablets labeled as containing wild honeysuckle flowers were actually made with leaves of the plant that were not cleaned properly.