Israel was responsible for at least 54 Palestinian deaths last year as it rejected hundreds of medical permit requests it received from Gaza residents seeking treatment outside the besieged strip, rights groups have said.

In a joint statement on Tuesday, the Gaza-based Al Mezan Center for Human Rights, Amnesty International, Human Rights Watch, Medical Aid for Palestinians (MAP), and Physicians for Human Rights Israel (PHRI), highlighted the immediate need for Israel to end its decade-long siege of the Gaza Strip.

In 2017, Israeli authorities approved fewer than half the medical permit requests it received, which were tied to appointments and treatment sessions in hospitals across the occupied territories and Israel - the lowest level since 2008.

More than 25,000 permit requests were submitted to Israeli authorities. Of those, 719 were refused, often under the pretext of security.

Another 11,281 applications are still pending approval - meaning thousands of people are in a state of jeopardy.

Samir Zaqout, Al Mezan director, told Al Jazeera that there is no "real rational reason" why patients in need of urgent medical assistance are denied hospital access.

"Israel is under a legal obligation to facilitate the freedom of movement of the Palestinian people," he said. "It decided when it blockaded the strip not only to deny Gazans of the right to free movement, but it also punished the ill who have a right to access healthcare."

In 2007, following the election victory of Hamas and the group's assumption of control over the territory, Israel imposed a strict land, aerial and naval blockade on Gaza.

In 2013, neighbouring Egypt, which has largely closed its border crossing with Gaza, blocked tunnels connecting Gaza with Egypt's el-Arish, shutting off the only other route out of the strip.

The main alternative is a path via the Erez crossing, which transfers people to Israel and the rest of the occupied territories.

'25,000 Gazans' on life's edge

Over the years, Israel has placed obstacles in the way of those seeking medical permits, which facilitate the movement of the ill.

For instance, child patients must have a guardian who is over 50 years old in order to travel.

Children with cancer without a guardian of the correct age, therefore, have not been able to access life-saving hospital appointments, Zaqout said.

Although Israel approves between 10 and 15 percent of permit requests, the bulk of the applications remains "under review" for months at a time, forcing many to reschedule appointments several times.

"The Israelis stall with the application requests and sometimes, not issuing a refusal at all makes it impossible for the patient to follow up with a lawyer or a rights organisation," Zaquot said.

Only patients who are in need of urgent care are eligible to apply for medical permits, meaning "more than 25,000 Gazans are between life and death".

'Who else do we turn to?'

Hani, father of seven-year-old cancer patient Ruba, said his daughter was recently denied a medical permit for the first time in seven years.

"She's not the only one," said Hani, who chose to conceal his last name for fear of reprisal.

"I had a daughter who died when she was just seven months old," he told Al Jazeera. "She suffered from the same cancer, and we lost her six years ago.

"I don't want to lose another daughter."

Ruba was diagnosed with cancer when she was a toddler.

She underwent a bone marrow transplant in January last year in a procedure that cost the family its savings.

Ruba received the tissue donation from her brother.

"I made sure it was my healthiest son, I wanted her to have the best chance of surviving," Hani said.

But without necessary treatment, he fears for his daughter's life.

"She's such a good girl, she's so pretty and smart," he said. "We're good people and do everything right - we face no problems with the authorities and our paperwork is always in order.

Hani said the family had received permits before on some 300 occasions and was not given a reason for the latest refusal.

"I don't even understand why, there were no reasons given to me this time, and I utilised every contact I had … nothing is more important to me than my children's wellbeing.

"Who else do we turn to?"

Israel has over the past decade launched three major assaults on Gaza, worsening a stark humanitarian situation.

With a major fuel and power crisis, the UN last week warned Gaza's emergency fuel supplies would soon run dry unless it received immediate donor support.

Fuel for generators to operate hospital supplies is largely absent.

Since 2008, Gaza's population has doubled while medical facilities remained poor.

With severe restrictions on access to basic services, Gaza has been dubbed the world's largest open-air prison.

Follow Farah Najjar on Twitter: @NajjarF91