Hamas prisoners in Israeli jails launched a hunger strike on Sunday morning to protest the installation of cellphone jamming technology in some prisons that has made it impossible to use smuggled cellphones in the wards.

The leaders of the strike have threatened to escalate the situation by refusing water if their demands for better incarceration conditions and the removal of the signal jamming systems are not met within seven days.

The strikers are led by a few of the most notorious terrorists Israel has ever put behind bars, according to a Channel 13 news report. They include Arman Mahamed, who is serving 36 life sentences for the Cafe Moment suicide bombing in central Jerusalem on March 9, 2002, which killed 11 and wounded 54; Hassan Salame, who is serving 84 life sentences for the bus 18 bombings in Jerusalem in 1996; and Muammar Abu Sheikh, who is serving 29 life sentences for his role in the bombing of the Park Hotel in Netanya on Passover Eve, March 27, 2002, which killed 30 and left 140 wounded.

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The strike comes a day after Public Security Minister Gilad Erdan, who oversees the prison system, denied there was a worsening of living conditions for the prisoners in recent months, but defended the jamming policy.

Speaking at a cultural event in Kfar Saba, he said it was “a crazy thing that terrorists in prison can be in contact with terror groups.”

A Prisons Service official said over the weekend that 14 separate incidents of illicit phone calls meant to instigate terror attacks were identified in recent months.

Erdan said the prisoners were seeking to use the threat of mass hospitalization to extract concessions.

He rejected holding negotiations with them and said he did not intend to “surrender” to their demands.

“This is the pressure that they are trying to apply. Believe me, terrorists dying from a hunger strike is the last thing that bothers me,” he said.

Erdan added that Israel would send additional medical personnel to prisons ahead of the strike to prevent the need for hospitalization.

“We are hoping that they’ll break before then,” he added.

On Sunday, the Israel Prisons Service said it would respond “forcefully and with determination” to ensure the strike did not achieve its aim of removing the jamming systems.

“Our assessment is that [the strike] will take place in stages,” a Prisons Service official said. “Each time a different group of prisoners will join the strike, replacing the group that preceded it. We know how to contain any action by the security prisoners, and we have the medical crews that can provide solutions if they are needed.”

The official added: “We will use tried and tested measures, such as immediate punishment for the leaders of the protest and the prisoners who participate. We will bolster our forces [in the prisons] to prevent escalation.”

Representatives of the prisoners have said in recent days that Israeli authorities had agreed to concessions in order to avoid the hunger strike. Israeli officials vehemently denied any such concessions had been offered.

There is concern that a mass hunger strike could increase military tensions with the Hamas terror group along the Gaza border, at a time when Egyptian mediators are seeking to secure a long-term ceasefire between the sides.

One prisoners’ representative said last week that the smuggled cellphones would not be used for terrorism, but to allow prisoners to speak with their families, and urged the installation of payphones in the ward.

“It doesn’t matter if the public phones are under surveillance, because we only want to speak to our families. If there’s a payphone we don’t need to smuggle cellphones.”

Prisoners are also said to be demanding family visitations from Gaza residents and more TV stations in the wards.

The representative told the Haaretz daily that Israeli authorities had agreed to hold further discussions after this week’s election.

Erdan’s office strongly denied that prisoners had been offered any incentives to avoid the strike.

The row over incarceration conditions has recently sparked violence.

Twice last month, Hamas prisoners violently attacked guards at Ketziot Prison, with one guard sustaining serious injuries from a stab wound to his neck. Reports in Hebrew-language media said that in the second attack, inmates used shanks to stab guards as the prisoners were being moved between cells, sparking a riot in the prison.

The Palestinian Prisoners Club has said that riots at Ketziot sparked by the crackdown have injured over 120 Palestinian inmates since February. According to the group, Israel Prisons Service officials have completely isolated several prisoners involved in the riot in “very dire conditions,” stripping them of their personal belongings, family visitation rights and interactions with other prisoners.

The IPS said that 11 prisoners were injured and hospitalized after security forces quelled a March 3 riot. Seven of the prisoners were airlifted to hospitals by the Israel Defense Forces, the Haaretz daily reported at the time.

On Monday, the United Nations’ envoy to the region, Nickolay Mladenov, reportedly discussed the issue of Palestinian prisoners during talks with Hamas leader Ismail Haniyeh in the Gaza Strip.

Israel’s Channel 13 quoted a Palestinian source as saying that Haniyeh warned Mladenov that the recent uptick in violence among prisoners could aggravate tensions with Israel.

Hamas officials reportedly asked Mladenov to intervene, and said that inmates were prepared to take unspecified measures if the Israeli “attacks” against them continued.

Erdan has called the recent violence “very serious,” and said it “proves once again that the prisons service is on the front line of the war against terror.”

He vowed to continue jamming cellphones in prisons, saying that it was an important step in attempts to prevent “terror attacks being directed from within the prison against Israeli civilians.”