Children of IS fighter Khaled Sharrouf want to go back to Australia

The orphaned children of an Australian Islamic State (IS) fighter who moved his family to Syria in 2013 are desperate to return to their "normal lives".

Khaled Sharrouf went to Syria to fight for IS in 2013, a year after he was released from jail for his part in a terror plot.

With their parents and two older brothers dying in March, 17-year-old Zaynab, 15-year-old Hoda and eight-year-old Humzeh are now in a refugee camp in northeastern Syria, ABC reports.

"I just want to get out of here," Zaynab told the ABC's Four Corners programme.

Children of IS fighter Khaled Sharrouf want to go back to Australia

Zaynab said they've been wanting to return home for a long time.

"We were just scared," she told the ABC. "People get raped, tortured."

The 17-year-old is seven-and-a-half months pregnant with her third child.

The children's maternal grandmother, Karen Nettleton, is on her third mission to bring them home.

She maintained sporadic contact with her grandchildren over the half-decade they were apart.

"We weren't the ones that chose to come here in the first place," Zaynab told the ABC.

"When my Mum told me we were in Syria, I started crying. I asked to go home every five seconds."

Somewhere between 3700 and 4600 foreign children were taken to Syria to join IS  representing about 10 percent of all foreigners and a further 730 were born there to foreign parents, according to the UK-based International Centre for the Study of Radicalisation.