Stallone did not enter his guilty plea in person

The actor, 60, admitted possessing the growth hormone Jintropin when he was stopped at Sydney airport in February.

Stallone had been in Australia to promote his film Rocky Balboa, but he was not in the Sydney court on Tuesday.

He will be sentenced next week, when he faces a maximum fine of A$22,000 ($18,330, �9,200) in court, much lower than if it had been a federal case.

In federal cases, the maximum penalty for importing a banned substance of this type is A$110,000 ($91,600) and five years in prison.

Prosecution documents said Stallone had marked "no" on a customs declaration form that asked if he was bringing restricted substances into the country.

HUMAN GROWTH HORMONE Made in the pituitary gland Stimulates growth in children Regulates metabolism in adults Medical uses include reversing muscle wastage in Aids patients Has been promoted as an anti-ageing treatment Jintropin is a synthetic version of the hormone Read more

But an X-ray of bags belonging to his entourage uncovered the bottles of Jintropin, which is made by Chinese firm GeneScience pharmaceuticals.

"You have not been validly prescribed the goods by a medical practitioner for any medical condition suffered by you and for which the goods are recognised medical treatment," Stallone was told in a customs document submitted to the court.