The grandfather of a seven-year-old boy pictured clutching the severed head of a Syrian soldier has urged the Australian government to bring the child home.

The photograph of a young boy holding the decapitated head of a slain Syrian soldier and published in Australian media underscored the barbarity of Islamist State militants, Australian prime minister Tony Abbott said.

Australia has issued arrest warrants for a pair of Australian citizens believed to be fighting in Syria, the Australian Broadcasting Corporation (ABC) reported, after images emerged of the two holding the severed heads of Syrian soldiers.

POLICE believe a nuclear reactor in southern Sydney was a possible target of a Sydney-based Islamic terror cell, according to details of Australia’s biggest-ever counter-terror investigation released yesterday.

Police believe a nuclear reactor in southern Sydney was a possible target of a Sydney-based Islamic terror cell, according to details of Australia’s biggest-ever counter-terror investigation released today.