The Palestinian militant turned theatre director Zakaria Zubeidi has resumed a total hunger strike in protest at his continued detention without charge by Palestinian security forces, and his supporters say he could die within days.

Zubeidi, who publicly renounced armed struggle in 2006 in favour of cultural resistance, has been held in prison in Jericho since 13 May after being detained in a wave of arrests in his home city of Jenin. He has not been charged with any offence.

He received assurances that he would be released, but at a court hearing on Monday his detention was extended by a further 19 days. He declared that he would refuse all food, fluids and medical attention.

According to witnesses, a visibly weak and thin Zubeidi told the court: "This morning the doctor told me I have three days to live if I don't drink water. So this court has decided to kill me."

Zubeidi's arrest followed an attack by gunmen on the home of Jenin's governor, who shortly afterwards died of a heart attack. A weapon used in the attack was linked by Palestinian investigators to Zubeidi. He denied any involvement and before his arrest he offered to co-operate with the investigation.

He told relatives and associates that he had been held in solitary confinement for the first 50 days of detention, had been denied access to a lawyer for more than two weeks and had been abused and tortured by interrogators. His lawyer, Farid Hawwash, was also arrested after criticising the Palestinian security forces.

Human Rights Watch criticised Zubeidi's continued detention. "For more than four months, the Palestinian Authority has violated Zubeidi's basic due process rights to be charged and tried, and continues to ignore his statements that interrogators tortured him," said Bill Van Esveld, of HRW.

"The PA's foreign donors should urgently pressure it to end the impunity and arbitrary detentions that Zubeidi's case exemplifies." Western governments including Britain and the US provide direct funding to the PA security services.

Zubeidi is a director and co-founder of Jenin's innovative but controversial Freedom Theatre. Jonatan Stanczak, managing director of the theatre, said: "I fear Zakaria will be the first Palestinian prisoner to die as a consequence of hunger strike – and the terrible thing is that he's in a Palestinian prison."

Jenny Nyman, the widow of Juliano Mer-Khamis, the theatre's founder who was shot dead 18 months ago, said: "It's a disaster and a disgrace for the PA. If they let a person who has fought all his life for the freedom of his people die in prison, it's a very dark period, and a big symbol of the state of Palestinian society."

Hawwash, Zubeidi's lawyer, said he would appeal against the decision in court in Ramallah on Wednesday, but had "no expectations" of the outcome.

Jenin was a bedrock of the second intifada, or Palestinian uprising, and the home of many suicide bombers sent to target Israeli citizens. Zubeidi was on Israel's most-wanted list as the leader of the al-Aqsa Martyrs Brigade in the city. But Jenin was later held up as a model of good Palestinian governance as the city prospered with economic investment and PA security forces won control from militant groups.

A string of attacks in the past 18 months – including the unsolved murder of Mer-Khamis, the assault on the governor's house and the assassination two weeks ago of the Palestinian security chief Hisham al-Rakh – has led to claims that Jenin is slipping towards anarchy.

The city's new governor, Talal Dwekat, denied there was a crisis. "There is no problem we're incapable of solving, and no person above the law," he said. "Years ago you would see gangsters and guns in Jenin, but now you walk around and the only guns you see are in the hands of the security forces. There is total control over Jenin."

Zubeidi's detention is another blow to the Freedom Theatre, which has been repeatedly raided by Israeli security forces since Mer-Khamis was killed. The theatre has antagonised both Israeli and Palestinian authorities by criticising their actions.

"The level of harassment from the Israeli army has been seriously affecting our work to the extent that it has even threatened our continuation," Stanczak said. "Now the PA is also causing problems by detaining Zakaria, but I don't know whether by intention or as a consequence. His detention makes the PA seem like another occupier rather than a servant of the people."

The theatre has been criticised by conservative elements in the Jenin refugee camp in which it is based over its mixed-gender acting workshops and progressive outlook. "We challenge power structures, we are provocative," Stanczak said. "If we didn't, what would be the purpose of our work?"

Dwekat said he had not received any complaints about the theatre since he became governor five months ago. "Even if the theatre makes mistakes, the reaction should not be violent. All our problems should be dealt with through dialogue. The PA is totally supportive of cultural activities." He said he planned to make his first visit to the theatre "very soon".