A Palestinian prisoner on a hunger strike, who could pose the first test of a new law in Israel allowing detainees to be force fed, was placed on an artificial respirator and given infusions after his lungs stopped working and he had seizures on Friday. There were fears that violent demonstrations could erupt as the health of the prisoner, Mohammad Allan, who began a hunger strike 60 days ago, deteriorated sharply. Mr. Allan, a 31-year-old lawyer, began his hunger strike on June 16 to protest his indefinite incarceration without known charges. The case has presented a sharp challenge to Israel's security establishment, which says the law is intended to save lives. Palestinians contend that the true purpose of the law, which was passed on July 30, is to prevent prisoners from using hunger strikes to demand better conditions or their release, which they say are their only means of protest while incarcerated. "In the early hours of this morning, there was a deterioration in Mohammad Allan's condition," said Ayelet Kedar, a spokeswoman for the Barzilai Medical Center in Ashkelon, Israel. "The patient is receiving medical treatment including ventilation and intravenous fluids and salts." "His condition is stable," said Ms. Kedar, who added that further testing would evaluate Mr. Allan's condition and would determine if further treatment is required. Giving an unconscious patient intravenous fluids is permitted by existing laws, said Dr. Ahmad Tibi, an Arab member of the Israeli Parliament who spoke from the medical center. Palestinian hunger strikers have usually allowed Israeli medics to intervene once they lose consciousness, at least to revive them. Mr. Tibi said the center had not sought to begin the process that would allow the force feeding of Mr. Allan. By law, that requires a doctor to conduct a physical examination, and the Israel Prison Service would have to present the results to a district court for approval. Jamil Khatib, one of the prisoner's lawyers, said that Mr. Allan was being given salts and potassium and that he could decide if he wanted to continue treatment once he recovered. "The hospital will not force him," Mr. Khatib said. Mr. Allan has expressly said that he does not want to be the subject of a medical examination or of intervention, and his mother has said that Mr. Allan wants to be released from incarceration or to die. His brother, Ameed, said by telephone that he was not aware that his sibling was being given intravenous fluids. As Mr. Allan received emergency treatment, his lawyers held discussions with intelligence officials about his fate, Mr. Khatib said. Among the questions was whether to release Mr. Allan, as he demands, to move forward with force-feeding him, or to let him die because of a lack of nutrients. "This is about ego," Mr. Khatib said by telephone from the Barzilai Medical Center. "Will Israel submit to the demands of a prisoner, or not?" Palestinian news outlets reported that prison authorities had declared a state of alert, closed cell blocks and prevented communal Muslim prayers on Friday, as a leading prisoner rights activist called for a "day of rage." A spokesman for Israel's prison service, speaking on the condition of anonymity in line with regulations, said that the agency was operating as usual and that no extraordinary changes had been made. Officials who met with Mr. Allan before he lost consciousness described him as gaunt and said that his vision was fading, that his hearing was declining and that he was vomiting water — the only thing he has consumed since beginning his fast. A photograph of Mr. Allan published on a Palestinian news website showed a withered, skinny bearded man lying in bed, his foot shackled to the hospital bed by a thin silver bracelet. Palestinian inmates most often use hunger strikes to protest "administrative detention," which enables the Israeli authorities to hold prisoners for six months and is sometimes renewed to prolong detention for years. In such cases, security officials typically present evidence only to judges, not to detainees or their lawyers. Israeli security officials say they cannot make charges public because doing so would expose their intelligence-gathering systems.