The Palestinian Prisoners' Club advocacy group said the Israel Prison Service (IPS), which on Monday warned of "serious consequences" for hunger strikers, was trying to break the open-ended hunger strike, which was initiated by prominent Palestinian leader Marwan Barghouti.
"During the first day of the strike, the prison service took several punitive measures against the prisoners by putting strike leaders in judicial confinement and transferring some prisoners to other prisons," Qadoura Fares, head of the Palestinian Prisoners' Club, told Anadolu Agency.
"Israeli authorities claim the decision [to cancel scheduled visits to prisoners] came due to the state of emergency declared in the prisons," he said.
The International Committee of the Red Cross (ICRC), for its part, which administers prison visits, confirmed that the IPS had informed it of its decision to cancel scheduled visits to hunger-striking prisoners.
ICRC spokesman Jesus Serrano Redondo told Anadolu Agency that the committee had told the Israeli authorities that all prisoners enjoyed protection under the Geneva Convention and thus had a right to receive visitors.
According to a Tuesday statement issued by strike organizers, authorities in Israel's Gilboa Prison had banned lawyers from visiting striking prisoners.
Ofer Zalzberg, a security analyst with the International Crisis Group -- a transnational NGO, told Anadolu Agency that Israel was now trying to avoid being forced into making any concessions as a result of the hunger strike.
"Israel is trying to de-incentivize future hunger strikes and is trying to basically embrace the 'no concession' policy… they are taking deterrent measures," Zalzberg said.
In the past, he said, Israel's attempts to force-feed hunger-striking prisoners had failed to stem repeated mass hunger strikes, which is why -- this time around -- it has set up medical facilities near the prisons.
"It really is about stamina on both sides. Israel knew about this imminent strike and prepared itself so it would have what it calls 'maximum stamina'," Zalzberg said.
"Prisoners are doing the same, so it's really about who cracks first," he added, noting that if more prisoners were to join the strike, the Israeli authorities may have trouble handling the large numbers.
More than 1,000 prisoners are now participating in the strike, which was launched Monday by Barghouti, who described it as a form of "non-violent resistance" against conditions faced by thousands of Palestinians in Israeli prisons.
Among the prisoners' chief demands is the installation of telephones in each prison, more frequent family visits, better healthcare and improved conditions for female prisoners.
Israeli media slammed a recent column by Barghouti that was published in the New York Times, in which he explained the rationale for his hunger strike, criticizing the newspaper for failing to mention that Barghouti had been jailed for murder as a leader of Fatah's armed wing.
The newspaper later changed its description of the Palestinian leader, also noting that he had refused to provide a defense at his trial as he did not recognize the court's legitimacy.
On Monday, the Israeli Foreign Ministry, for its part, complained that jailed Palestinians should not be described as "political prisoners".
"They are convicted terrorists and murderers. They were brought to justice and are treated properly under international law," ministry spokesman Emmanuel Nahshon said in a statement.
The open-ended strike was launched on Monday to coincide with Palestinian Prisoners Day amid calls by detainees for more frequent prison visits, better medical care and better treatment for female prisoners.
Roughly 6,500 Palestinian prisoners are now languishing in Israeli prisons, according to Palestinian figures.
