Police in China are trying to trace 90 million drug capsules laced with the toxic metal chromium that have been sold on the open market, in the latest product safety scandal to hit the country.

Eleven people in Zhejiang province were arrested following the discovery that the capsules - which pharmaceutical companies use for their drugs - were tainted with the poison.

Police, along with food and drug authorities in Ninghai county, seized more than 440,000 chromium-laced capsules from an illegal workshop on July 22.

They also confiscated more than 100kg of semi-finished capsules and more than 700kg of capsule material made from industrial gelatin containing the toxin, according to a Zhejiang newspaper hosted by official news agency Xinhua.

An investigation by police found that from February to July the workshop produced about 90 million capsules which contained chromium far exceeding safety levels for edible gelatin.

The entire stock was sold.

The illegal workshop’s owner, identified by his surname Pan had hired 10 people from the county who were involved in a tainted capsule scandal in 2012, the report said.

Pan and the 10 employees were detained on August 29 for producing and selling a poisonous product.

Ninghai police are still tracking down where the tainted capsules have ended up.

There have been no reports of death or illness caused by taking the tainted capsules, but chromium can cause serious damage to organs.

Police said the capsules were sold to four people, possibly distributors, who are now at the centre of a manhunt.

In 2012, authorities detained 45 people, arrested nine and seized more than 77 million capsules contaminated with chromium.

The factories involved in the drug capsules scandal in 2012 were in Hebei province and Pan’s home county, Xinchang.

China has been beset by food and drug safety scandals in recent years.

Last Friday, authorities arrested six employees of a Shanghai food supplier to McDonald’s and other major restaurant chains in China for selling expired meat.

Last week, Zhejiang authorities confiscated 30,000 tonnes of chicken feet found soaking in hydrogen peroxide, which can cause irritation when consumed in unsafe levels.

In 2008, at least six children died and nearly 300,000 became ill after taking baby formula tainted by melamine, a chemical added by milk companies to boost protein levels.