Prisoners on a hunger strike at Guantanamo Bay say their jailers are denying them bottled water and forcing them to drink non-potable tap water, as an international Red Cross committee visited on a fact-finding mission.

Military guards have kept the camp cold and denied drinkable water to end the prisoners’ hunger strike, according to an emergency motion filed in federal court, the Associated Press reports.

“The reality is that these men are slowly withering away and we as a country need to take immediate action,” said human rights lawyer Mari Newman, who was among those who submitted the motion.

The lawyers claimed in their motion that the lack of bottled water ”already caused some prisoners kidney, urinary and stomach problems,” according to AP.

But a spokesman for the prison said not only is the tap water safe, but prisoners are still being provided with bottled water.

“It’s potable water. It’s the same water I make my coffee with and that they make lunch with,” Navy Capt. Robert Durand said.

About 31 of the 166 prisoners had joined the hunger strike as of Wednesday, according to AP. Several were being treated to prevent severe dehydration and weight loss. Prison lawyers say the protest started on February 6 over what the prisoners say is harsh treatment and indefinite detention without charges, according to AP.  The military says nothing has changed, and the prisoners are trying to draw attention to their situation.