Ashton Kutcher and Mila Kunis have taken their romance Down Under

Ashton Kutcher and Mila Kunis

The 'Two And A Half Men' actor - who has been dating his former 'That 70s' co-star for six months - opted to mix business with pleasure by taking his 29-year-old girlfriend along on a work related trip to Australia.

The 34-year-old actor hosted a star-studded dinner in Sydney - with guests including Brian McFadden, Mel B and model Ruby Rose - to promote his successful business investment Airbnb.

But the actor also made time to enjoy the local sights with Mila and the couple were spotted checking out the Wild Life Sydney Zoo.

A source told Australia's Daily Telegraph: "They never requested anything and just enjoyed a typical experience. It was just the two of them and while they didn't want any photos taken, they were very pleasant and friendly."

The actor - who is currently the highest paid actor on TV - is reportedly dragging out his divorce to Demi Moore and is refusing to budge on the financial terms of their separation and how they should divide their assets.

Demi is said to be devastated that he has moved on so quickly since their split last November, especially with 'Ted' star Mila, whom he has known for 14 years and was recently named Sexiest Woman Alive.