Ruby Rose sports backless black dress at the Sydney premiere of Pitch Perfect 3... after fans express concerns amid reports her weight has dropped to 'just 44kg'

She sparked concern among fans when she displayed a slimmer physique at the ARIA Awards earlier this week.

But Ruby Rose put on a defiant display when she attended the Sydney premiere of her latest film, Pitch Perfect 3, on Wednesday, donning a shimmery black dress.

The 31-year-old's actress made a statement in the strapless number, which highlighted her extensive body art.

She wore her brunette bob slicked back from her face and accessorised with a silver necklace.