Australia’s most prominent female Muslim activist, an outspoken critic of her country’s immigration policies, was denied entry into the United States at Minneapolis-St. Paul International Airport on Wednesday.

Yassmin Abdel-Magied, 27, an award-winning author and broadcaster, was scheduled to speak next week at the PEN World Voices Festival in New York. When she arrived at the Twin Cities airport around 4 p.m., she said on Twitter, she was detained by border agents.

“I’m currently at the border and they’ve said I’m being deported,” Abdel-Magied wrote on Twitter. “This should be fun. What are my rights?”

The agents, she said, told her they had canceled her visa and required her to return to London, where she lives.

U.S. authorities said Abdel-Magied was denied entry because she did not disclose that she was being paid to speak at the conference, a violation of her visitor’s visa.

In a statement posted on Twitter on Thursday, she said she was also to present at an event hosted by Minneapolis-based Target Corp. In an e-mail to the Star Tribune, Target confirmed that she was to speak at an internal event.

Abdel-Magied said that while waiting in a holding room before her return flight to Europe, she passed the time painting her nails and reading a book. “My heart’s been on double time for the last three hours,” she said when reached via Twitter as she waited for her return flight. “The system isn’t set up for people like me.”

Abdel-Magied said she had visited the U.S. many times on the same visa without issue.

She has spoken in the United States, she said, at events for Chevron and the Inter-American Development Bank. She was last in the United States in February, she said, on the same visa to speak at a conference for Twitter.

Abdel-Magied said she was traveling with a B1/B2 visa. That document allows foreign nationals to visit the United States to attend “scientific, educational, professional, or business convention or conference,” according to the State Department. But it prohibits paid performances or “any professional performance before a paying audience.”

In a statement, the U.S. Customs and Border Protection agency said Abdel-Magied did not have an appropriate visa for paid work.

“The traveler is eligible to reapply for a visa for future visits,” the statement read.

Abdel-Magied is the daughter of Sudanese immigrants to Australia. She has been an outspoken critic of Australia’s refugee and immigration policy and writes regularly about her experiences as both a Muslim and a feminist.

In 2017, Abdel-Magied moved to London, after a backlash over a Facebook post she wrote critiquing Australia’s refugee detention policy on Anzac Day, a national day of remembrance of the country’s war dead. Conservative commentators criticized the post as insensitive. She has called herself “Australia’s most publicly hated Muslim.”

Abdel-Magied had planned to speak on two panels at the PEN World Voices Festival: one on her experiences as a Muslim woman in a Western country and another on online harassment.

In a statement, the festival’s organizers called for her to be admitted to the United States.