Sylvester Stallone has pleaded guilty to importing a banned human growth hormone into Australia.

The Hollywood star admitted possessing the illegal substance Jintropin when he was stopped by customs at Sydney airport in February.

"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.

Stallone, 60, had been in the country to promote his latest film Rocky Balboa.

He faces a maximum fine of A$22,000 ($18,330/�9,200) when sentenced in court next week