Hundreds of Palestinian prisoners are said to have resumed a hunger strike protest after a weekend break.
Palestinians have protested in support of the strikers
An Israeli prison service official confirmed that between 350 and 400 prisoners were again refusing meals at Shikma prison in the town of Ashkelon.
But he said they were still eating and drinking from supplies they had stockpiled over the weekend.
Palestinians say about 4,000 inmates have been fasting for more than two weeks to protest about jail conditions.
While the prisoners in Ashkelon stopped their strike for two days, claiming to have won concessions from Israeli officials, the others have continued the protest for 16 continuous days, Palestinians say.
Palestinian Negotiations Minister Saeb Erekat said he had called for European Union help to force Israel to improve its treatment of prisoners.
He added that "their life is now in danger after 16
days on hunger strike".
But Israeli officials dispute the details and numbers involved in the strike, saying many prisoners never began striking, and that hundreds of others have ended their fasts.