SINGAPORE - The Health Sciences Authority (HSA) has seized about $21,000 worth of illegal health products in a 10-day crackdown.

Eight people are assisting HSA in the investigations, the agency said.

From May 29 to June 7, HSA scrutinised Singapore websites that sell potentially dangerous health products.

It seized more than 25,000 products including anabolic steroids, sleeping pills, pregnancy test kits, and medicinal drugs for infertility and weight loss.

One of the biggest hauls were 5,812 units of anabolic steroids with a street value of about $13,000.

Three suspects were selling the prescription-only medicines on e-commerce websites and local gyms at double the price they had paid.

They marketed them as being able to increase muscle mass, strength and help with weight loss.

Anabolic steroids mimic the effects of the male hormone, testosterone, and are used to treat hormonal deficiency conditions.

They are not approved for use to boost athletic performance or increase muscle mass, HSA said.

The steroids can cause side effects such as insomnia, irritability, aggressive behaviour, hypertension, liver cancer, development of prominent breasts in men and impotence.

The HSA raids were part of Operation Pangea, an Interpol-led exercise against the illegal online sale of counterfeit and unlicensed medicines.

HSA has also been working with major online retailers and internet forums to remove posts selling illegal health products.

It cautioned that the products consumers receive may turn out to be illegal, counterfeit or substandard, and may contain potent undeclared ingredients which could be harmful to one's health.

More information on the dangers of taking health products from dubious sources can be found at www.healthdangers.sg.

HSA was one of 193 agencies from 103 countries participating in Operation Pangea.