Zambian authorities arrested an ex-information minister and three journalists for old stories that were critical of the then opposition leader and now president Michael Sata.

Ex-minister Ronnie Shikapwasha was charged with abuse of office for telling public television to air documentaries discrediting Sata in the run up to the 2011 elections.

"Being an employee in the ministry, he arbitrarily and in disregard of defamation laws and ZNBC editorial policy did direct the board and management to air 'Stand up for Zambia' documentaries, an act prejudicial to the rights and interest of ZNBC," said Namukolo Kasumpa, spokeswoman for the anti-corruption taskforce.

Stories written from the series of documentaries were also published in the local pro-government press.

Investigative journalist Chanda Chimba, who produced the documentaries, was arrested for the publication of the stories and for allegedly receiving payment for the stories.

Davis Mataka, a former managing director of state-owned Zambia Daily Mail and Ngande Mwanajiti, a media consultant, were also taken in and jointly charged for publishing an unregistered private, but pro-government, newspaper ahead of the elections which were won by Sata.

The four were later freed on bail.

Since assuming office in 2011, Sata has embarked on an anti-corruption drive, probing deals by his predecessor government, arresting former ministers and diplomats.