The bust was the result of a four-year investigation which was launched in 2012 and conducted in collaboration with the Spanish Guardia Civil due to the underground network’s close ties with neighbouring Spain.
The investigation was carried out throughout Portugal and involved 34 searches.
Twenty people were made formal suspects in the proceedings which culminated in six drug-producing and selling networks being shut down.
As well as the confiscation of 750,000 tablets some 50,000 injectable ampoules were seized, along with machinery used to produce, package and label the tablets, and the respective paraphernalia such as bottles and recipes.
In Spain, 55 people were detained in connection to the investigation.
Anabolic steroids are drugs that are structurally related to the cyclic steroid rings system and have similar effects to testosterone in the body.
Anabolic steroids were first made in the 1930s, and are now used therapeutically in medicine to stimulate muscle growth and appetite, induce male puberty and treat chronic wasting conditions, such as cancer and AIDS.
However, they are also used – mostly illegally – within sports to improve muscle mass, strength and athletic performance.