The highly anticipated second season of SAS Australia will premiere later this year.

And on Wednesday, chief instructor Ant Middleton was all smiles as he left KIIS FM's headquarters in Sydney after an interview on The Kyle and Jackie O Show.

The former British Special Forces solider, 40, cut a casual figure as he left the studios following a chat about the new series.

Ant wore a grey jumper, white T-shirt and black jeans for his visit to KIIS FM.

He teamed the casual ensemble with a pair of black sneakers, a matching cap and a wristwatch.

During his chat with Kyle and Jackie O, Ant revealed a 'good few' celebrities quit the show, which recently finished filming in the Blue Mountains, within the first few days.

'I've never done so much shouting in my life and spitting at people's faces so they frustrated me a lot but we got so much out of them,' he said.

'A good few dropped in the first couple of days, but once we get them in that mindset and headspace you see a change in them,' he added.

Ant also told radio hosts Kyle Sandilands and Jackie 'O' Henderson that former NRL star Sam Burgess was 'someone we had to get a grip of'.

Season two's line-up for the gruelling competition features a mixture of famous and controversial participants.

Ex-Rabbitohs player Sam is set to appear on the show alongside socialite Brynne Edelsten and celebrity chef Manu Feildel.

Tennis champion Alicia Molik, Home and Away's Dan Ewing, actress Bonnie Anderson and former politician Emma Husar are also set to compete on the show.

They'll be joined by TV presenter Erin Holland, AFL star Heath Shaw, actress Isabelle Cornish, Olympian Jana Pittman and Australian sprinter Jessica Peris.

The series will also star Ironman Jett Kenny, Olympic runner John Steffensen, volleyball champion Kerri Pottharst, Bra Boy Koby Abberton, singer Pete Murray and tennis star Mark Philippoussis.

The celebrities will endure strenuous physical activity and military-inspired challenges in order to test their true character.