Joe Jonas thinks of Delta Goodrem like a ''sister'' after she dated his younger brother Nick Jonas.

The DNCE singer appears alongside Delta, 33, on the judging panel for 'The Voice Australia', and has said that after the ''princess of Australia'' dated his brother Nick for 10 months in 2012, the pair have their own ''brother and sister'' bond.

When asked if it was ''awkward'' working with Delta after her romance with 25-year-old Nick, Joe said: ''Delta and I go way back. I met her when I was probably 13 or 14. We've never had an opportunity to collaborate, to make music, to perform together. She is the princess of Australia so it's nice to have her on my side. And on this show, of course, we go back and forth, like any brother and sister might.''

The 28-year-old singer appears on the singing competition alongside fellow musical stars Boy George and Kelly Rowland, and has said he jumped at the chance to work on the show with artists he ''appreciates''.

Asked by Stellar magazine why he took on 'The Voice Australia', he said: ''It was nice to know that I would have a friend here - I've known Delta for many years. I get to share a stage every day with Boy George. I get to know Kelly Rowland. It was the chance to work with these artists that I appreciate - and then to see how much talent Australia has. I'm dumbfounded. You're sitting there like, 'Why are these not the biggest stars in the world right now?'''

Meanwhile, Joe - who is engaged to 'Game of Thrones' star Sophie Turner - recently admitted he teases his younger brother Nick about his romance with Delta.

He said: ''There's a few times it has been brought up and luckily it's like a brother-and-sister relationship (between) me and her and we can really mess with each other and have a good time.''