TEHRAN — An Iranian appeals court has upheld jail sentences of up to 10 years against eight environmentalists convicted of spying, conspiring with Washington and damaging national security, the judiciary said Tuesday.

"The appeals court endorsed and finalized the sentences of the suspects in the so-called environmentalists' case, as we believe it to be a case of acting against national security," judiciary spokesman Gholamhossein Esmaili said.

The eight were handed sentences of four to 10 years, with Morad Tahbaz and Niloufar Bayani receiving the maximum for "conspiring with America as a hostile government", Esmaili said.

Houman Jowkar and Taher Ghadirian were sentenced to eight years, and Sam Rajabi and Sepideh Kashani to six on similar charges.

Amir Hossein Khaleqi was charged with "spying" and sentenced to six years, while Abdolreza Kouhpayeh was sentenced to four years for "colluding to commit acts against national security", Esmaili said.

The convicts all worked with environmental group Persian Wildlife Heritage Foundation to track endangered species and were arrested on suspicion of espionage in early 2018.

Four of them were later charged with "corruption on earth" — an offense that is one of the most serious under Iranian law and carries the death penalty.

Those charges were dropped last October, but the defendants still faced other security-related charges.

Another environmentalist detained in early 2018, Iranian-Canadian university professor Kavous Seyed Emami, 63, allegedly committed suicide in prison a fortnight after his arrest.

His widow, Maryam Mombeini, left Iran for Canada in October after a months-long travel ban was lifted. — AFP