Istanbul, Turkey (CNN) -- Turkish authorities have detained  American activist and freelance journalist Jake Hess in the  southeastern, predominantly Kurdish city of Diyarbakir.
 At a  court appearance Sunday, a prosecutor charged Hess with "taking orders  from a terrorist organization" and called for his immediate deportation  from Turkey, witnesses said.
 Turkish officialdom regularly refers to the Kurdistan Workers' Party, or PKK, as a terrorist organization.
 U.S. diplomats say Hess rejected their offer of assistance after he was taken into custody.
 "We  have spoken with him on the phone regarding his situation, and he  specifically asked us not to share any information on his case," said  Deborah Guido, a spokeswoman for the U.S. Embassy in Ankara. "He did not  sign a privacy waiver. We can take an oral privacy waiver [by phone],  and it was his choice. He did not want to be helped."
 Asked why  he rejected the American offer, Hess answered that "the U.S. is an  imperialist country, and I disagree with U.S. policy towards Turkey and  the Kurds. It would be hypocritical to support an American journalist  who is persecuted for human rights journalism while at the same time  supporting the Turkish policy of criminalizing Kurdish political  activists."
 Hess spoke with CNN by telephone on Monday from the  detention center in Diyarbakir. He said he was initially detained by a  Turkish anti-terrorist police unit on August 11.
 "I am being  targeted for criticizing the Turkish government and criticizing human  rights abuses," he said. "The prosecutor accused me of waging a smear  campaign against the Turkish republic."
 Turkish officials in Diyarbakir and in the capital, Ankara, have declined to comment on Hess' case.
 The  25-year old American said he hoped his detention would focus attention  on the arrest of hundreds of ethnic Kurds in recent years, including  elected mayors from Turkey's Peace and Democracy Party (BDP), a Kurdish  nationalist political party.
 "Some of these people have been in  custody since April 2009 without trial," he said. "It's an absolutely  unbelievable and outrageous injustice."
 Hess is a native of New Hampshire who studied at Suffolk University and Brown University.
 He  said he previously volunteered as an activist with several Kurdish  activist organizations in Europe and in Turkey. After moving to  Diyarbakir more than a year ago, Hess volunteered with the Human Rights  Association (IHD), a local non-governmental organization that has  reported extensively on abuses committed against ethnic Kurds during  Turkey's quarter-century long war with PKK guerrillas. More than 30,000  people, most of them ethnic Kurds, have been killed in the conflict.
 Hess  had also begun writing as a freelance journalist with the online Inter  Press Service news agency, filing a report this month from Iraqi  Kurdistan about periodic Turkish and Iranian artillery bombardment of  Kurdish villages on the Iraqi side of the border.
 Hess denied  charges that he was an active accomplice to the PKK, which is formally  classified by the Turkish and U.S. governments as a terrorist  organization.
 "The only relationship I had with the PKK was maybe  two months ago, when I went to northern Iraq and interviewed a PKK  spokesman there," Hess said.
 Media watchdog organizations are demanding Hess's release.
 "We  call for Hess's immediate release. Neither placing him in pre-trial  detention nor deporting him are appropriate solutions," said the  Paris-based group Reporters Without Borders in a statement.
 "Kurdish  media and journalists who cover the consequences of Turkish policy  towards the Kurds are too often the target of harassment, which the  authorities clumsily try to justify as a necessary part of their efforts  to combat terrorism."
 Turkish police also briefly detained  several other residents of Diyarbakir in connection with Hess's case,  including Yilmaz Akinci, a respected Kurdish journalist who has worked  with Reuters, National Public Radio, ABC News and CNN, and who is now a  producer with Al Jazeera's Arabic language service.
 Akinci said Hess approached him in June, looking for work.
 "He had been applying for jobs everywhere," Akinci said. "He came to me and said, 'I want to be a journalist.' "
 Turkish  police detained Akinci at his family's home in a predawn raid Sunday.  He said he later learned that security forces had secretly photographed  him during his earlier meeting with Hess.
 Akinci said he was released later Sunday, after authorities learned that he was a journalist.