(CNN) The fate of dozens of chimpanzees used in American biomedical experiments is up in the air after resources for their care and feeding were withdrawn this year.

The New York Blood Center, in partnership with the Liberian government, funded hepatitis research and other medical studies at the Liberian Institute for Biomedical Research beginning in 1974.

When the blood center decided 10 years ago to discontinue chimp research at the Vilab II facilities near Monrovia, it continued to pay for upkeep of the primates, which were set free to roam on several nearby islands.

In January, the blood center gave the institute notice that it would no longer pay to care for the animals, and in March, the organization pulled funding, which sent the institute scrambling for resources to keep feeding them.

"NYBC's support of the chimpanzees was entirely voluntary, offered on a philanthropic basis to permit discussions regarding Liberia's need to fulfill their responsibilities until the Government of Liberia could take over," the center said in a statement on its website . "The Government of Liberia and animal rights organizations knew all along that our support was voluntary and could not continue."

Not so, say animal rights groups and the head of the Liberian Institute for Biomedical Research, who contend that the blood center has reneged on its obligation to care for the animals throughout their lives. The animals are being "left to die from starvation in retirement," Fatorma Bolay, who runs the research institute, told Front Page Africa Online

"It is appalling that the New York Blood Center is trying to wipe its hands of any responsibility for this colony of chimpanzees that they created and used for their own profit," Kathleen Conlee, vice president of animal research issues at the Humane Society of the United States, said in a statement

The animals would never have been used by the Liberian facility in testing if not for the funding and partnership of the blood center, Conlee told CNN.

The center, which declined to comment on the situation beyond pointing to statements on its website, is in arbitration with the Liberian government over care of the chimpanzees.

While the center claims it tried to no avail to work with the Liberian government and animal rights groups to generate a new funding source for the chimps, the Humane Society says the blood center will not respond to its recent efforts to partner up.

The Humane Society is now collaborating with the Liberian Institute for Biomedical Research to care for the animals.

The 64 chimps, who cannot swim, are confined to several mangrove islands in the Farmington River that lack appropriate natural food resources. Vice magazine filmed a 2014 documentary on the chimpanzees and the Vilab II project in the area, which locals call "Monkey Island."

Some of the animals were caught in the wild to be used for medical testing, while others were purchased after being kept as pets. Having spent most of their lives in captivity, the chimps are not suitable to live in the wild and will need care and feeding for years to come.

Private donors and animal protection groups have stepped in to fill the gap after New York Blood Center funding dried up.

The Humane Society started a Go Fund Me campaign with a $150,000 goal, which has been surpassed, as a stopgap to feed the animals temporarily in hopes that the blood center would eventually resume support. But that hasn't happened, and the Humane Society is making plans to further care for the animals.

The organization is sending a team to the area in three weeks, Conlee said, to outline a plan to make the islands into a real sanctuary for the chimpanzees, complete with reliable food and water sources and shelter. Workers would also like access to the animals for medical care, which isn't possible with the current setup. Two of the chimps have died recently, she said.

More funds are are crucial to the effort.

The blood center has been the target of ire from animal advocates and those who believe that after it profited from the chimps, the organization should see to their care until they die. Legendary primatologist Jane Goodall has added her voice to the chorus of calls for the center to continue its support of the animals.

Change.org petition demanding that the New York Blood Center resume caring for the animals is approaching 200,000 signatures. The Humane Society started a "Save the Abandoned Chimps" Facebook page, which has nearly 10,000 followers.

The center says it never promised to care for the chimps in perpetuity, despite unauthorized statements to the contrary by a former center official (PDF). The group puts the onus on the Liberian government.

"NYBC does not own the animals in question, and never did," the blood center says on its website . "The animals are owned by the Liberian government, and their officials have repeatedly acknowledged that they have responsibility for the care of the chimpanzees."

Current efforts to care for the animals require a team of 25 who make daily trips to the island with nearly 500 pounds of food, at a cost of $20,000 per month, according to the Humane Society.

The chimps' diet consists of bananas, potato leaves, sweet potatoes, plantains, coconuts, palm nuts and other fruits and vegetables, in addition to rice balls fortified with powdered milk.

The lack of potable water on the island is a real problem, Conlee said, and caretakers must ferry water as well as food. Water systems connected to five of six tanks that workers fill with clean water weren't functioning and needed to be repaired when the Humane Society arrived.

The animals, who have names like Samantha, Mabel, Bullet, Joyce, Stewart, Duno, Hellen, Ellie, Annie and Teta, according to a BBC report , have become close to their caretakers.

Conlee praised workers like Joseph Thomas, who has looked after the animals for 36 years and continued to do so on a volunteer basis after the blood center pulled its support. The Humane Society is trying to make sure workers are compensated.

"They are committed to and excited about this phase of providing the animals with better care," Conlee said.