Sylvester Stallone pleaded guilty Tuesday to two charges of importing banned substances into Australia, saying he takes the muscle-building drugs for a medical condition and didn't know he was breaking the law.
Stallone, star of the "Rocky" and "Rambo" films, didn't appear in court. He left Australia in February after authorities confiscated the substances.
"I made a terrible mistake, not because I was attempting to deceive anyone, but I was simply ignorant to your official rules," the 60-year-old actor said in a letter to Sydney Local Court.
"Years ago I was diagnosed with a condition and my doctors prescribed human growth hormone and testosterone for its treatment. Under medical supervision I have continued to use both medications," he said.
Stallone didn't disclose the medical condition.
His lawyer, Phillip Boulten, said the actor had been taking the drugs for at least six years, and didn't realize he needed a license to bring them into Australia.
"This is not some back-alley body builder dealing covertly with some banned substance in some sort of secret way," he said. "This was a legitimate medical condition being treated by doctors of the top-ranking order in the West Coast of the United States."
Stallone doesn't face prison time because of the relatively minor nature of the crime. He could be fined thousands of dollars when he is sentenced Monday.
He was charged after a customs search of his luggage in February revealed 48 vials of the human growth drug Jintropin.
Three days later, Stallone threw four vials out a window of his Sydney hotel when customs officials arrived to search his room, prosecutor David Agius told the court.
Stallone said he was carrying a large number of vials because he was going on location in Thailand for three months for a new movie.
Human growth hormone, a naturally occurring substance that can be replicated synthetically and is used to build muscle mass, is considered a performance-enhancing drug in Australia. It cannot be imported without a permit.
The maximum penalty for bringing Jintropin into Australia without a license is a fine of $91,500 and five years in prison. Stallone faces a maximum penalty of $18,000 on each of the two charges and no prison time because the matter is being heard by a local, not federal, court.
Human growth hormone is available in Australia and the United States by prescription to treat specific medical conditions such as hormone deficiency and stunted growth in children.
The drugs are more widely available in the United States, where proponents say their benefits can range from helping athletes increase muscle mass to restoring energy in the elderly. There is no scientific consensus on the claimed benefits.