In a statement, Amnesty said Calixto Martinez was detained for his work reporting for the non-governmental news agency Hablemos Press and has been held without charge since Sept. 16, 2012.
Anne Wood, director of Mercy Corps, one of the few non-governmental agencies still operating in Kandahar, said her agency was still trying to carry out field work as discreetly as possible.
But Alexander von Bismarck, from the Environmental Investigation Agency (EIA), a non-governmental organisation or NGO, says the main beneficiaries are Chinese mafiosi and businessmen.