An investigation is under way in Australia into claims that navy sailors competed with each other to bed their female colleagues for cash prizes.
According to Channel Seven news, sailors on board HMAS Success put a cash value on each woman's head.
Sleeping with a female officer or a lesbian, or having sex in a strange place, won more money, the report said.
The Defence Department confirmed that a number of individuals had been sent back to Australia for interviews.
HMAS Success, which has a crew of 220, is currently on exercises in South East Asia.
According to the Channel Seven report, the contest came to light in May, when the vessel was in Singapore.
It said that the sailors recorded their efforts in a book called The Ledger, challenging each other to sleep with as many female colleagues as possible.
Sex on a pool table or with a lesbian reportedly scored higher points.
The Defence Department did not confirm how many sailors were involved.
But, in a statement to Seven Network, it said that a number of concerns raised by female crew members were "now subject to formal inquiry".
The "veracity of any allegations" had yet to be confirmed, it said.