JERUSALEM — The loss of life of a preferred activist whereas within the custody of the Palestinian Authority on Thursday has infuriated Palestinians throughout the West Financial institution, set off a big protest in Ramallah and put a highlight on a current crackdown on the authorities’ opponents.

The activist, Nizar Banat, 42, was recognized for his fierce on-line criticism of the authority, the Palestinian authorities that workouts restricted self-autonomy in components of the West Financial institution. His household says he was fatally crushed by Palestinian safety forces.

The authority has not given a full accounting of what occurred however mentioned his well being “deteriorated” throughout his arrest and has promised an investigation.

An investigative committee might be given all the knowledge it must “allow it to proceed with its work” and to “expedite the method of exposing the reality,” mentioned Mohammed Shtayyeh, the prime minister of the authority.

The authority, dealing with sharp criticism over the cancellation of nationwide elections and a resurgence of recognition for its rival, Hamas, has not too long ago arrested dozens of its opponents across the occupied West Financial institution.

Mr. Banat’s loss of life, coming throughout that push, has posed a brand new disaster for the authority, whose standing has plummeted up to now couple of months because it canceled what would have been the first legislative and presidential elections in 15 years and watched Hamas’s reputation take off final month when it attacked Israel with rockets. Mr. Banat had been a candidate in these parliamentary elections.

His loss of life highlighted the rising chasm between senior Palestinian officers — a lot of whom reside in costly houses, profit from particular Israeli permits and infrequently specific unquestioned fealty to Mahmoud Abbas, the authority’s president — and the broader Palestinian public, which bears the brunt of the Israeli occupation.

Palestinians throughout the West Financial institution have more and more expressed frustration with what they describe as their authorities’s oppressive and authoritarian ways aimed toward quashing freedom of speech.

“It’s clear that we reside below a corrupt system that’s waging warfare towards anybody who criticizes it,” mentioned Ammar Banat, 27, a cousin of Nizar Banat. “Suffice it to say that we’re not solely residing below an Israeli occupation however a Palestinian one, too.”

Nizar Banat was a home painter, however had a following on-line for his acerbic commentary, together with criticism of the authority’s relations with Israel. From his residence in Dura, a village south of Hebron within the West Financial institution, he would publish feedback that few would dare to make however that usually resonated with the broader public.

Ammar Banat and different members of the family mentioned a big contingent of safety officers compelled its method into a house the place Mr. Banat was staying in central Hebron early Thursday. He had been residing there, in an Israeli-controlled a part of the town, for a lot of the previous seven weeks after his residence in Dura was shot at, his cousin mentioned.

The family members mentioned the Palestinian forces beat him viciously, doused him with pepper spray, insulted him and dragged him on the bottom.

Hours later, after calling pals within the safety providers to inspect Mr. Banat’s situation and in search of him at native hospitals, the household discovered that he was useless, Ammar Banat mentioned. Nizar Banat had been in “wonderful heath,” his cousin added.

The Palestinian Authority has not launched an in depth account of what triggered Mr. Banat’s loss of life, and declined to reply questions.

On Thursday night, Ammar Al-Dwaik, the director of the Unbiased Fee for Human Rights, mentioned at a information convention that two medical doctors at an post-mortem known as it “an unnatural loss of life,” with bruises and abrasions on many areas of his physique, together with the pinnacle and neck.

Jibrin al-Bakri, the Palestinian governor within the Hebron area, mentioned in a brief assertion that Mr. Banat’s well being had “deteriorated” throughout his arrest. He mentioned Mr. Banat was instantly transferred to a hospital, the place medical doctors decided he was useless.

The U.S. State Division weighed in on Mr. Banat’s loss of life on Thursday night. “We’re deeply disturbed by the loss of life of Palestinian activist Nizar Banat and the knowledge that has been reported concerning the circumstances of his loss of life,” the State Division spokesman, Ned Worth, mentioned in a press release. He urged a “thorough and clear investigation” and mentioned the USA had “severe considerations about Palestinian Authority restrictions on the train of freedom of expression by Palestinians and harassment of civil society activists and organizations.”

Mr. Banat continuously posted movies on his Fb web page wherein he would criticize the administration and insurance policies of officers like Mr. Shtayyeh.

This week, he lashed out on the Palestinian Authority for making a cope with Israel to amass vaccines, a few of which had been nearing their expiration date. The authority ultimately rejected the deal.

In late April, he blasted Mr. Abbas for declaring he would solely enable parliamentary and presidential elections to happen if Israel accredited permitting voting in East Jerusalem.

“You need to punish Israel by depriving the Palestinian individuals of elections,” Mr. Banat mentioned. “What sort of stupidity is that this?”

Along with criticizing the authority, Mr. Banat would take intention at Israel; at Mohammed Dahlan, an exiled rival of Mr. Abbas; and the L.G.B.T. neighborhood.

Mr. Banat’s loss of life got here amid a broad arrest marketing campaign by the authority wherein at the least 50 individuals have been arrested over their political actions, mentioned Muhannad Karaja, the director of Legal professionals for Justice, a authorized assist group.

The authority has moved to suppress Palestinian critics, Mr. Karaja mentioned, as a result of it feels notably “weak” within the wake of its choice to cancel the elections and “marginalized” by the current enhance in Hamas’s reputation.

Some have put the depend of these detained at a considerably increased quantity. Dimitri Diliani, a Fatah member allied with Mr. Dahlan, mentioned the authority has detained 170 activists related to Mr. Dahlan since late Might, when Secretary of State Antony J. Blinken visited Ramallah.

“Blinken’s go to gave a lift to an remoted president,” Mr. Diliani mentioned, referring to Mr. Abbas. “Blinken’s go to made them really feel robust sufficient to commit atrocities.”

On the protest on Thursday afternoon in Ramallah, safety forces blocked some streets within the metropolis, tried to disperse crowds by firing tear gasoline and hit at the least one man with picket batons. Individuals chanted for the “fall of the regime” and mentioned “Get out, get out, Abbas.”

Hamas, the militant group that controls the Gaza Strip, condemned what it known as Mr. Banat’s “assassination” and mentioned it amounted to an “organized and deliberate crime that displays the intentions and conduct of Abbas’s authority and his safety providers towards our individuals and opposition activists.”

Ammar Banat mentioned his cousin had not too long ago acquired a sequence of threats from Fatah and Palestinian Authority safety officers within the Hebron space.

“They had been set on taking him out,” he mentioned. “I’ve little question that they needed to kill him.”

Isabel Kershner contributed reporting.