DUBAI - A senior Iranian judiciary official has dismissed reports that a US-Iranian journalist being held in Tehran will soon be released, saying his case was still under investigation, Tasnim news agency reported on Tuesday.The United States and human rights organizations have called on Iran to release The Washington Post journalist Jason Rezaian, who was detained on July 22 and is being held without charge. He has worked for the Post in Tehran since 2012.The secretary general of Iran's High Council for Human Rights, Mohammad Javad Larijani, told the Euronews TV channel last week that Rezaian could be released "in less than a month".But Iran's deputy judiciary chief, Hadi Sadeghi, said his case was still at preliminary stages."Rezaian's case is still under investigation, which can take more than a month. Nothing definite can be said about his case," Sadeghi told Tasnim."It will be up to the judge to decide whether to drop the case or to charge him. What Mr. Larijani meant was the time needed for the investigation."Analysts say Rezaian is being used by Iranian hardliners to scuttle the Rouhani administrations attempts to negotiate with the West over its nuclear program and to embarrass him abroad.Some hardline Iranian media have accused Rezaian of spying for the United States. Under Iran's Islamic law, spying is punishable by death sentence.