In a tweet, the Zimbabwe Lawyers for Human Rights (ZLHR) group said Ms O'Donovan - the manager of Magamba TV, an online-based satirical video outlet - was the first person to be arrested on such grounds since the ministry was formed.

Police arrested Ms O'Donovan during a dawn raid at her home in Zimbabwe's capital, Harare, seizing electronic devices, including computers and a phone, ZLHR's Obey Shava said in a statement.

Police had not yet charged her but they alleged that "tweets emanating from her IT address are insulting to the president", Mr Shava was quoted by the Associated Press news agency as saying.

Mr Shava referred to some tweets sent from Ms O'Donovan's account which referred to a Goblin, whose step-son recently bought a Rolls Royce, but said that Mr Mugabe was not mentioned, reports the BBC's Shingayi Nyoka from Harare.

Zimbabwe does not yet have a cyber-crime law, so if O'Donovan is charged it is likely to be under the presidential insult law, she adds. Hundreds of people have been arrested over the years under this law, our reporter says.