"The 14-year-old daughter of one of Australia's most wanted terrorists has reportedly been married off to his best friend.

The teenager apparently bragged online about her marriage with Mohamed Elomar, 30, posting pictures online.

“Young cubs of ISIS, may Allah protect them from all evil,” Sharrouf's daughter apparently wrote.

Khaled Sharouf shot to notoriety in August when he posted an image online of his seven-year-old son holding the severed head of a slain Syrian soldier.

Both Australians have been accused of enslaving and raping women from the Yazidi religious minority in northern Iraq.

Two women who say they escaped from the pair have accused the jihadists of purchasing women from a slave market and forcing them into marriage.

They said the Australians, who are fighting for the Islamic State group in Syria, bought them from a slave market after they were kidnapped in Iraq and taken deep into Syrian territory last year.

The women said the Australians held them captive along with thousands of others.

One of them told the ABC that Sharrouf, who has been convicted and jailed for his involvement in a terrorist plot in Australia, threatened to kill her.

"At night he was taking a girl downstairs, and when the girl returned she'd tell us, `he told me you have to marry me or else I will sell you, and if you say anything

to my wife I will sell you or kill you'," she said in January.