0600 GMT April 23, 2019
Isa Kalantari, head of Department of the Environment, said that the conclusion had been reached by a special four-man committee set up to investigate the allegations against the activists, including the ministers of justice, interior and intelligence, and the president's legal deputy, ISNA reported.
"This four-member group has come to the conclusion that these detained individuals are in custody without having done anything and naturally they must be freed soon," Kalantari said.
Iran detained several environmentalists and wildlife activists earlier this year on espionage charges.
Judiciary officials had earlier announced that the activists were gathering sensitive information for foreign governments under the guise of scientific and environmental activities.