Thor star Chris Hemsworth has been surprised – and put on the spot – on air by one of his former Home and Away co-stars.

The actor, who played Kim Hyde from 2004 to 2007 on the soap, was doing an interview on Nova FM in Australia when a listener named Kate phoned in.

Kate asked him: "I know these days you get to work with people like, I don't know, Olivia Wilde and Natalie Portman, but back in your Home and Away days... who was the woman you just absolutely adored working with and would you, in fact, swap Natalie Portman for any day?"

Hemsworth, realising who Kate was, replied: "I would have to say Kate Ritchie [who plays Sally]. She was not only the most talented, but just the most stunning woman..."

Listen to the banter here.

Hemsworth also paid tribute to the soap, saying: "I loved Home and Away and I credit everything I do to it. I was 19 when I started working on that show. I had such a great time."