(AFP) – A self-described Australian “Islamic Bonnie and Clyde” couple were Wednesday charged with planning a terrorist act, which reportedly involved a Sydney stabbing attack.

The pair, Sameh Bayda and Alo-Bridget Namoa, both 19, were already in custody accused of collecting documents likely to facilitate terrorist acts.

“Today’s charges follow an extensive investigation by officers from the NSW Joint Counter Terrorism Team and on-going consultation with the Commonwealth DPP,” New South Wales state police said in a statement.

“The charge carries a penalty of life imprisonment.”

The Sydney couple, reportedly husband and wife, were arrested about a year ago.

At the time, Bayda was allegedly found with Arabic documents on how to carry out a stabbing and how to make an improvised explosive device (IED), the Sydney Morning Herald said.

Namoa allegedly had in her possession an Islamic flag and hunting knife, as well as instructions in Arabic on making a IED detonator, the Australian Broadcasting Corporation reported, adding that in a text message conversation with Bayda, she described them as the “Islamic Bonnie and Clyde”.

Both were denied bail with the case due back in court on March 15, a Central Local Court official in Sydney told AFP.

Canberra has become increasingly worried about homegrown extremism and the terror threat level was raised in September 2014.

Australian officials say they have prevented 11 terror attacks on home soil in the past two years. But some have gone ahead, including the murder of a Sydney police employee in 2015 by a 15-year-old boy.

Counter-terror police have made a series of arrests since late 2014, with the youth and radicalisation of many of those detained a growing concern for authorities.