A court in Peru has revoked parole for an American woman who was imprisoned for aiding a left-wing rebel group.
Lori Berenson turned herself into police after judges ordered that she be sent back to prison to finish the last five years of her 20-year sentence.
On Monday, Berenson apologised for collaborating with the Tupac Amaru Revolutionary Movement and pleaded for her parole to be upheld.
But she denied having been a member or participating in any "violent acts".
"If my participation contributed to societal violence I am very sorry for this," the 40-year-old added.
As part of its insurgency, the Tupac Amaru robbed banks, kidnapped and killed a number of people in the 1980s and 90s.
The Marxist group was active at the same time as the Shining Path guerrillas, who unleashed a brutal civil conflict in which nearly 70,000 people were killed.
The daughter of university professors from New York, Berenson travelled to Central and South America in the 1990s.
During her travels, she is believed to have made contact with the Tupac Amaru.
She was arrested in November 1995 after she gained access to the Peruvian Congress on false journalist credentials alongside the wife of the Tupac Amaru leader.
Military prosecutors accused her of gathering information for a rebel plot to kidnap members of Congress and exchange them for imprisoned rebel leaders.
She was convicted of treason by a military court in 1996 and sentenced to life in prison. But she was retried in a civilian court after pressure from the US government.
In 2001, she was found guilty of the lesser crime of terrorist collaboration and imprisoned for 20 years, five of which she had already served. Her family maintained she was a social activist who was wrongfully convicted.
She gave birth to a son, Salvador, in prison in May 2009, and was released under parole a year later after a judge determined that she had exhibited good behaviour.
Berenson had recently moved into a rented flat in the Miraflores district of the capital, Lima.
However, polls suggested Peruvians widely disapproved of the decision to release her, and prosecutors told the three-judge panel at a criminal appeals court that the arguments for doing so were riddled with errors.
On Wednesday, the court said it had based its decision to revoke her parole on a failure by other legal authorities to verify addresses in Lima that she had provided them.
Hours after the ruling Berenson turned herself into police, her husband and lawyer Anibal Apari Sanchez said.
"The only thing I can tell you is that Lori Berenson hasn't fled the country," the former Tupac Amaru member told reporters outside the US embassy, according to the Associated Press. "Even though she disagrees with the court's decision, she has turned herself in."
He added: "She's calm. She is a very strong woman. She is going to return to jail with her baby."