The woman, identified as Allison Fluke-Ekren, formerly of the US state of Kansas, had been named in a sealed criminal complaint filed in 2019 in a federal Virginia court, the government statement said.

Among other things, it said she had planned an attack on a US college campus and spoke of organizing a devastating attack on an American shopping mall.

The statement said the 42-year-old Fluke-Ekren -- who has used at least five aliases -- had been apprehended previously in Syria but was transferred into FBI custody on Friday.

She is expected to make her initial appearance before the US District Court for Eastern Virginia, in the Washington suburb of Alexandria, on Monday at 2:00 pm (1900 GMT), the statement said.

- All-female IS unit -

Fluke-Ekren traveled to Syria "several years ago for the purpose of committing or supporting terrorism," the government statement said, adding that she had "allegedly been involved with a number of terrorism-related activities on behalf of ISIS from at least 2014."

Those activities included planning and recruiting operatives for a possible attack on a US college campus, the statement said, though it provided no further details.

It also said she was the appointed leader and organizer of an all-female IS military battalion, where she trained women in using AK-47 assault rifles, grenades and suicide belts. Called the Khatiba Nusaybah, the members were all married to male IS fighters.

As battalion leader, the Justice Department alleges, she prepared the women to defend themselves during the 2017 siege of the IS stronghold of Raqqa, Syria.

Her other work for IS, the department said, included training children in the use of AK-47 rifles and suicide belts.

The statement said at least six individuals had observed Fluke-Ekren's "alleged terrorist conduct from at least 2014 through approximately 2017."

They said she had spoken of her desire to attack an American shopping mall by parking an explosives-packed vehicle in a basement garage.

"Fluke-Ekren allegedly considered any attack that did not kill a large number of individuals to be a waste of resources," the statement said.

ABC News, citing court papers, said Fluke-Ekren had moved to Egypt in 2008. She traveled frequently to the United States over the next three years but had not been back since 2011.

If convicted of the charges, Fluke-Ekren faces a maximum penalty of 20 years in prison.

Women make up only about 10 percent of people charged by the United States with supporting the Islamic State group, according to a study by the Program on Extremism at George Washington University. This is the first case involving someone accused of holding such a powerful position in IS.