US Customs and Border Protection has said Australian activist Yassmin Abdel-Magied, 27, was refused entry to the US because she had the wrong visa.
On Thursday morning, Australia time, Ms Abdel-Magied tweeted from Minneapolis that "within a few min of looking at my case the border security person... looking at my case she announces: 'we're sending you back!'".
But in a statement to SBS News, a spokesperson for US Customs and Border Protection said "during the inspection, CBP officers determined this individual did not possess the appropriate visa to receive monetary compensation for the speaking engagements she had planned during her visit to the United States."
Yassmin Abdel-Magied tweet. Source: @yassmin_a
"As such, she was deemed inadmissible to enter the United States for her visit, but was allowed to withdraw her application for admission. The traveler is eligible to reapply for a visa for future visits.”
Ms Abdel-Magied, a Sudanese-Australian who recently moved to London, was due to speak at two events at writers association PEN America's World Voices Festival in New York next week.
One of the talks, titled "The M Word: No Country For Young Muslim Women" was due to be about the "particularly heavy burden" of being a young, Muslim female in western countries.
She tweeted the ordeal from Minneapolis as it was occurring.
"They've taken my phone, cancelled my visa and are deporting me," she said.
She did not say which country she had been in before flying into the US.
"Those who say the world is borderless are those who have the right colour passports - or birthplace."
SBS News contacted Ms Abdel-Magied and her management for comment.
"There won’t be any interviews with Yassmin until this situation is sorted out," her management said.
"Funniest thing is that throughout this whole ordeal all I am thinking about is what a good story this will make. We all have ways of dealing with situations," she said.
Ms Abdel-Magied tweeted that after roughly three hours since she touched down in Minneapolis, she was on a plane leaving the US.
In a statement, PEN America chief executive officer Suzanne Nossel said she was "dismayed" at the news.
"We understand that Yassmin was travelling on a type of visa that she had used in the past for similar trips without issue," Ms Nossel said.
"We call on Customs and Border Patrol to admit her to the US so that she can take her rightful place in the urgent international conversation to take place at the festival next week."
PEN America is an author and human rights festival celebrating creative expression in the US and around the world.
Ms Abdel-Magied moved to London in 2017 after making a series of controversial claims including that "Islam to me is the most feminist religion".
She also suffered a public backlash after her Anzac Day post on social media which said: "Lest We Forget (Manus, Nauru, Syria, Palestine ...)".
The post was deleted from her Facebook page a few hours later, with Ms Abdel-Magied apologising and acknowledging "that the timing and nature of the post was disrespectful'.
Yassmin Abdel-Magied during a Q&A appearance on the ABC. Source: ABC Australia
Her apparent deportation from the US comes after the US Supreme Court last December gave the green light to President Donald Trump's controversial travel ban that targets people from six Muslim-majority countries.
The ban was subject to several legal challenges after opponents said it was in violation of the US Constitution because it discriminates against Muslims.
Australia's Citizenship and Multicultural Affairs Minister Alan Tudge said US visas were a decision for the American government.
"At the end of the day it is unusual for an Australian citizen to not be granted a visa to go into the United States, but I simply don't know the details behind this particular case," he said.
- with AAP
