HARARE (Reuters) - A high court judge in Zimbabwe said on Thursday the state s case against a U.S. citizen charged with trying to subvert President Robert Mugabe s government lacked facts and ordered that she be granted bail. Martha O Donovan has been in prison since Saturday, a day after she was arrested on accusations of insulting Mugabe in a Twitter post. Police later leveled the more serious charge of subversion, which carries a possible 20-year jail term. She denies both charges. O Donovan works for Magamba TV, which describes itself as Zimbabwe s leading producer of political satire. In granting her bail, High Court Judge Clement Phiri said there was a  patent absence of facts  in the state s case.  The applicant has demonstrated that she should be granted bail. It is my finding that it is in the interests of justice that the applicant be given bail,  Phiri said. O Donovan was not in court. Phiri ordered her to deposit $1,000 with the court, surrender her passport and report to the criminal investigations department twice a week as part of her bail conditions. Her lawyer Obey Shava said O Donovan would be released on Friday after completing administrative procedures. Amnesty International said in a statement the case showed that Zimbabwean authorities had contempt for freedom of expression. The state s case centers on a Twitter post it says she wrote in October calling Mugabe a  selfish and sick man . The government set up a Ministry of Cyber Security last month. Zimbabwe is facing acute shortages of foreign exchange and cash. The country is also concerned with who will succeed Mugabe, 93, who has ruled since independence from Britain in 1980. He plans to contest next year s election. This week Mugabe fired his deputy Emmerson Mnangagwa from the government and ruling party for  disloyalty . Mnangagawa was seen as a potential successor.  Formal opposition to Mugabe is limited but the government is wary of social media. Last year, activists including pastor Evan Mawarire used it to organize the #ThisFlag movement. Its stay-at-home demonstration was the biggest protest in a decade. 