Omar Nazzal, 54 a member of the Palestinian Journalists' Union, was arrested on April 23 at the border between the Israeli-occupied West Bank and Jordan, from where he had been due to fly to a European Federation of Journalists gathering in Bosnia.
His initial four-month detention was extended for three months in August and he was expected to be released tomorrow, his wife Marlene Rabadi told AFP.
"But the court informed us that his detention would be extended again," she said.
The Israeli army did not immediately respond to a request for comment.
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Israel insists that Nazzal was detained for "his involvement in terror group activities", not "because of his activity as a journalist".
He is accused of being in the Popular Front for the Liberation of Palestine (PFLP), a leftist party banned by Israel.
Under Israel's controversial administrative detention laws, the state can hold suspects for renewable six-month periods without charge or providing evidence to their lawyers.
The United Nations frequently calls on Israel to either charge or release those held under administrative detention.
In addition to Nazzal, another 19 journalists or journalism students are being held by Israel, including one the Palestinian Journalists' Union says has been in custody for more than 20 years.