(CNN)Wildlife officials in Malaysia are mourning the death of Iman, the country's last Sumatran rhino.
The female rhino, who was estimated to be about 25 years old, died Saturday at the Borneo Rhino Sanctuary in Tabin Wildlife Reserve, the Sabah Wildlife Department confirmed to CNN.
She has been at the sanctuary since she was captured in 2014, in Malaysia's Sabah state, part of the island of Borneo.
"Iman was given the very best care and attention since her capture in March 2014 right up to the moment she passed," State Tourism, Culture and Environment Minister Datuk Christina Liew said in a statement. "No one could have done more."
She had cancer, which was starting to cause her considerable pain because a tumor was putting pressure on her bladder, Sabah Wildlife Department director Augustine Tuuga said in the statement.
The Borneo Rhino Alliance (BORA), which operates the sanctuary, described Iman as "the sweetest soul, who brought so much joy and hope to all of us," in a Facebook post after her death.
"We are in so much pain right now, but we are thankful that you are no longer in pain," the post said. "May we be as strong as you in our urgent fight to save your species. May we be as courageous as you to never give up."
Tam, Malaysia's last male Sumatran rhino, died in May after suffering organ failure.
Conservationists had hoped to breed Tam and Iman, but those efforts were unsuccessful.
The Sumatran rhino is listed as critically endangered by the World Wildlife Fund and the International Rhino Foundation estimates that there are less than 80 alive in the world.
"We are saddened by today's news and on behalf of the International Rhino Foundation, we offer condolences to the Government of Sabah and our colleagues at the Borneo Rhino Alliance team on their loss," said Susie Ellis, executive director of the International Rhino Foundation in a statement.
They are the smallest living rhinoceroses and the only Asian rhino with two horns.
The remaining animals live in Indonesia, where they are under heavy guard to protect against poachers, according to the foundation.