The family of a political activist who died in the custody of Palestinian security forces last month on Saturday accused the Palestinian Authority of trying to cover up his death.

Relatives of Nazir Banat said they still have not received a document with an official cause of death and said the Palestinian Authority has made efforts to settle the matter out of court.

“The behavior of the Palestinian Authority until this moment is criminal behavior, covering up a crime,’’ Ghassan Banat, Nazir’s brother, told reporters.

Nazir Banat was an outspoken critic of the Palestinian Authority who called on Western nations to stop providing aid to the PA due to human rights violations and growing authoritarianism.

In a series of posts and live videos on Facebook, Banat had criticized the authority’s close security coordination with Israel, seen by many Palestinians as betrayal, and its corruption. He also lashed out at President Mahmoud Abbas in April for calling off what would have been the first Palestinian elections in 15 years. Banat was a candidate on an opposition slate.

His family has said security forces stormed into Banat’s bedroom while he was sleeping and beat him, inflicting bloody head wounds before removing him from the house. He died shortly afterward while in custody.

His death has prompted weeks of protests. On July 5 at least six activists were arrested by security forces when protesting outside the Palestinian Authority headquarters. Multiple witnesses said the police used pepper spray and beat the protesters with batons.

Some 150 people demonstrated in Ramallah on Saturday evening, holding up posters of Banat and chanting anti-Abbas slogans. The protest was peaceful and there were no reports of violence or arrests.

The Palestinian Authority, seen as a crucial partner of the U.S. and other Western countries, has formed an investigative committee into Banat’s death. His brother said that weeks later, the family has heard little from the government.

The Palestinian Authority has not responded to requests for comment.

‘‘Until this moment, we have failed to obtain a death certificate. How can you have a citizen who dies without issuing a death certificate?” Ghassan Banat said.

Accompanied by two family lawyers, the brother rejected what he said were attempts by the authority to send tribal elders to the family in hopes of closing the case and stopping it from reaching the courts.

“This file will not be resolved or closed through elders or tribal ways,” he said. “Nizar’s file is a political assassination and will remain open until justice is achieved, even if it takes 1,000 years.”

The Palestinian Authority is widely viewed as corrupt and authoritarian, with a recent poll last month showing that support for Abbas, who took power for what was supposed to be a four-year term in 2005, had nosedived.

Abbas has faced mounting pressure after calling off the elections when it appeared that his Fatah party would suffer a crushing defeat to the rival Hamas militant group.

Last month, Palestinian security forces arrested prominent activist and critic, Issa Amro, after he criticized recent arrests on Facebook.

(AP)