Zimbabwe police have arrested a United States citizen for insulting President Robert Mugabe on Twitter, embassy spokesman David McGuire told The Associated Press.

The police have not yet charged Martha O'Donovan who had been working with local social media outlet Magamba TV, whose target audience is youth.

Mugabe last month appointed a minister for cybersecurity, a move criticized by activists as aimed at clamping down on social media users.

Local human rights defenders say around 200 people are charged for allegedly insulting the president.