The Palestinian Prisoners' Club said 39 Palestinians had been arrested and placed under administrative detention for periods of between two and six months, while the other 45 had their detention prolonged.
Last Friday, journalist Mohammed al-Qiq ended a 94-day hunger strike staged in protest at his administrative detention under a deal for his release in May.
The procedure, which dates back to the British mandate of Palestine, allows Israel to hold suspects without trial for renewable six-month periods.
The Prisoners' Club, which follows their cases, said it was the highest number since 2009.
