The Indian Council of Medical Research (ICMR( on Monday directed states to stop using rapid antibody test kits procured from China-based Guangzhou Wondfo Biotech and Zhuhai Livzon Diagnostics after their results showed wide variations.

The statement came several states raised concerns over the performance of tests during the exercise that they undertook.

Following the complaints, ICMR said it evaluated the kits of the two firms in field conditions. "The results showed wide variation in their sensitivity, despite early promise of good performance for surveillance purposes," it said in a statement.

"In view of this, states are advised to stop using these kits procured from the above-mentioned companies and return them to be sent back to the suppliers."

ICMR had provided rapid antibody test kits to states with clear instructions that they are to be used only for surveillance purposes.