Imprisoned water charges protesters will step up their hunger strike from this morning by refusing fluids in opposition to their transfer to Wheatfield Prison.
The men - Derek Byrne, Paul Moore and Damien O'Neill, who are serving jail sentences for breaching a High Court order - all started refusing food over the weekend.
A fourth man, Michael Batty, remains out of the country receiving medical treatment, while Bernie Hughes is serving her sentence in the Dóchas Centre women's unit.
A family member of Mr Byrne's last night said the jailed protester was planning to refuse fluids from this morning.
"His spirits are good. His main concern is for his two children at the moment. He has been refusing food since Friday and said in his statement he would go off fluids from Monday.
"That is still the case," she said.
A statement was issued on Facebook on Saturday on behalf of Mr Byrne and the other hunger strikers.
The men vowed to refuse fluids until they are returned to Mountjoy, which is closer to their homes and easier for their families to visit.
"We were moved out of Mountjoy because of a political decision. We have taken the steps to go on hunger strike and have been on hunger strike since yesterday," the men said.
"If we are not moved back to Mountjoy Training Unit, as we were told we would be, then on Monday morning we will be taking it further and refusing fluids until we are moved back to Mountjoy."
Last night, Jessica Hughes, the daughter of Bernie Hughes who has been incarcerated in the Dóchas Centre women's unit, said her mother was not planning to join the other men in their hunger strike.
"I can only speak on behalf of my mother and she's in good spirits and is being treated well. She's not considering going on hunger strike," she said.
The developments come as thousands of people took to the streets once again in protests in Dublin and another outside the Fine Gael party conference in Co Mayo. Yesterday, a smaller protest of around 150 people took place outside Wheatfield Prison where demonstrators called for Derek Byrne, Paul Moore and Damien O'Neill to be returned to Mountjoy Prison.
Socialist TD Paul Murphy, who has come under fire for his involvement in protests against the water meters, said it had "passed off peacefully".
He said he understood the men were being kept in isolated cells and "locked down for 23 hours a day".
Between 5,000 and 7,000 people were reported to have taken part in a march in solidarity with the five water charges protesters in Dublin city centre on Saturday.
The march began outside the Central Bank and continued north out of the city centre, finishing outside Mountjoy Prison where a number of speakers addressed the crowd.
Another protest of around 200 people took place in the Taoiseach's home town of Castlebar on Saturday night.
The crowds gathered outside Enda Kenny's constituency office before moving to the TF Royal Hotel where the Fine Gael National Conference was held.