LONDON (Reuters) – The British government on Wednesday called on Iran to release environmentalist Morad Tahbaz, an Iranian-American who also holds British citizenship, after his family said he had been returned to prison. Tahbaz was arrested in 2018 and sentenced to 10 years in prison for “assembly and collusion against Iran’s national security” and working for the United States as a spy. He was briefly released on furlough in March when two dual nationals, including British-Iranian aid worker Nazanin Zaghari-Ratcliffe, were allowed to leave Iran. In July his lawyer was quoted as saying he had…