Amnesty International has called on Iran’s authorities to free eight environmentalists detained for more than a year.

In a statement on Tuesday, Amnesty said the detainees are being held on “trumped-up” spying charges. The environmentalists are awaiting verdicts after what Amnesty called a “grossly unfair trial” in January.

“There is evidence that they were subjected to torture and other ill-treatment including through prolonged solitary confinement in order to extract forced ‘confessions’,” the organization said.

The scientists of the Persian Wildlife Heritage Foundation were arrested in January. The head of the Foundation, University of Tehran professor Kavous Sayed-Emami, died in suspicious circumstances in Evin Prison two weeks after the detentions.

Iranian authorities said Sayed-Emami commit suicide, but his family and activists believe he was killed.

Four other environmentalists were charged last year with “sowing corruption on Earth” a charge that can carry the death penalty.

Three are accused of espionage and one is charged with “cooperating with hostile states” and “gathering and colluding to commit crimes against national security”. They could be given sentences of up to 11 years.

The environmentalists were monitoring the movement of endangered animals such as the Asiatic cheetah and the Persian leopard when they were detained. Amnesty’s Philip Luther said:

Protecting endangered wildlife is not a crime. These conservationists are scientists who were carrying out legitimate research. It is absurd that they have been prosecuted without any evidence and are being treated as criminals.

Iran’s authorities should release them immediately and unconditionally and drop the outrageous espionage-related charges against them.

One of the eight, Morad Tahbaz, is an Iranian-American dual national. The other scientists are Taher Ghadirian, Niloufar Bayani, Amirhossein Khaleghi, Houman Jokar, Sam Rajabi, Sepideh Kashani, and Abdolreza Kouhpayeh.

The United Nations Environment Program issued a statement on Wednesday supporting the calls for release of the scientists:

UN Environment continues to be concerned by the on-going detentions, and reported trials, of eight environmental workers in Iran, and has shared its concerns with the authorities in Tehran. Information we have recently received that some detainees may not have adequate access to legal counsel and representation is deeply troubling….

We know how much Iranians treasure their natural heritage, and we call on the government to protect the rights of all dedicated servants of the country’s unique environment, which are guaranteed by Iran’s laws and constitution.