An Adelaide woman has been charged with being a member of terrorist organisation Islamic State.

Federal and state police say the 22-year-old was arrested on Tuesday after an investigation run by the South Australian Joint Counter Terrorism Team that began in mid-2016.

They allege the woman, from the city’s western suburbs, cultivated relationships with Islamic State members online and has pledged her allegiance to the extremists.

But the agencies say the charge she is facing does not relate to planning a terrorist attack and stressed there is no known link between her and the explosions in Manchester.

She is in police custody ahead of a court appearance on Tuesday afternoon or Wednesday morning.

AFP Assistant Commissioner Counter Terrorism Ian McCartney says there is no current threat to SA or Australia more broadly from the incident but notes it is concerning young people remain susceptible to extremist ideologies.

“The arrest today highlights the global nature of terrorism” he told reporters in Adelaide.

He says the woman, an Australian citizen who came from Somalia as a teenager, first came to the attention of authorities in July last year while trying to fly out of Australia.

She was stopped from leaving the country and police have been investigating her since, with the majority of her dealings with Islamic State being online where she connected with terrorism suspects around the world.

SA Police Deputy Commissioner Linda Williams said investigators have been making constant risk assessments about the woman and would have arrested her sooner if they had believed she posed any threat to the community.

“I emphasise there wasn’t and there’s still no ongoing risk from this arrest,” she told reporters.

“We are comfortable this was the right time to make the arrest.”