Khalida Jarrar was scheduled to be released on June 30. But her husband, Ghassan, said Sunday that her lawyer was informed of the extension by Israeli authorities.
In 2017, the Shin Bet internal security service said Jarrar was arrested, along with a Palestinian activist near the West Bank city of Ramallah, for "promoting terror activities," without elaborating.
Jarrar is being held under “administrative detention,” an Israeli policy that permits holding people for months at a time without charges.
In 2015, she served 15 months after being convicted of incitement to violence and “promoting terror activities.”
Jarrar, a senior member of the Popular Front for the Liberation of Palestine (PFLP), was arrested again last year and has remained in administrative detention.
The United States, Canada, Australia, and the European Union all have designated the PFLP as a terrorist organization.
The group was involved in hijackings and other major attacks in the 1970s.
Her husband calls it a “political” detention.
Jarrar, 55, is a popular figure among Palestinians and is known for fiery speeches against Israel. Among other things, Jarrar has called for the kidnapping of Israeli soldiers.