Before being released from prison in May, Berenson served about 15 years of a 20-year sentence for collaborating with the Tupac Amaru Revolutionary Movement, or MRTA, a guerrilla group.

A justice ministry official said a panel of judges ruled her release was flawed because police neglected to confirm the location of her apartment in Lima where she would be living while on parole. Berenson could be released from prison again after the issue is cleared up, he said.

Her release had provoked controversy in a country still traumatized by a conflict that killed some 70,000 people. The MRTA was active in the 1980s and '90s when a larger insurgency, the Maoist Shining Path, also tried to topple the government.

A New York native who studied at the elite Massachusetts Institute of Technology before becoming involved in social justice issues in Latin America, Berenson was arrested on a bus in Peru in 1995 and charged with belonging to the MRTA.

In a rare public statement, Berenson, 40, was televised on Monday at a court hearing publicly apologizing for working with the MRTA.

"Yes, I collaborated with the MRTA. I was never a leader or a militant. I never participated in violent or bloody acts. I never killed anybody," she told a panel of judges.

(Reporting by Teresa Cespedes; Writing by Terry Wade, Editing by Jackie Frank)