Nicaraguan police have seized more than 40,000 tubes of Chinese-made toothpaste suspected of containing a chemical that killed at least 51 people in Panama last year, the health minister said Thursday.

All U.S. imports of Chinese toothpaste were halted last week to test for diethylene glycol — a chemical commonly used in antifreeze and brake fluid.

Nicaraguan Health Minister Maritza Cuan told a news conference that officials fear as many as 80,000 tubes may still be on the market. Cuan said the seized toothpaste, labeled "Excel" and "Mr. Cool," had been brought in from neighboring Costa Rica by importers who were unaware the tubes were tainted.

The tubes originated in Panama, which received shipments of the toothpaste last year.

Costa Rica and Panama ordered the toothpaste pulled from shelves there earlier this month after finding it contained diethylene glycol.

Businesses in Panama, not China were "mainly responsible" for passing off an industrial chemical as a medical ingredient last year, leading to the deaths of at least 51 people, a senior official in China's product-inspection agency said Thursday.

Wei Chuanzhong, vice minister of the Administration for Quality Supervision, Inspection and Quarantine, said Chinese companies sold the industrial solvent called 'TD glycerin', to Spanish companies who then sold it to Panamanian companies. The product was then used to make cough syrup and other medicine.