A man faced a Sydney court today charged with having sexual relations with a rabbit and the sadistic killing of 17 other rabbits whose carcasses were found dumped in a lane in The Rocks.

Brendan Francis McMahon, 36, of Edward Street, North Sydney, appeared briefly before Central Local Court Magistrate Allan Moore today charged with having allegedly committed the offences over the past three weeks.

McMahon, a New Zealand born finance company director, sat quietly in the dock during the hearing at which he was represented by barrister Doug Marr.

No plea was entered to a total of 21 charges laid by The Rocks Police against McMahon, a business partner with Jason Meares, the former brother-in-law of James Packer.

McMahon, who's company website claims he is a former Bachelor of the Year winner, was arrested by detectives from The Rocks Police at a house in Tamarama early today.

The investigation began after skinned and partially-skinned dead and dying rabbits began to appear in a laneway off York Street, near Circular Quay in late July.