By Ayla Jean Yackley and Humeyra Pamuk
ISTANBUL (Reuters) - Turkish authorities detained journalists, a politician and a pollster on Wednesday and issued arrest warrants for another 105 people over suspected links to a U.S.-based Islamic cleric blamed for a failed coup on July 15.
Opposition politicians warned the latest wave of arrests may target government critics with no clear links to the religious movement led by Fethullah Gulen, a preacher accused by Turkey of masterminding the abortive putsch. He denies any involvement.
Three journalists working for the nationalist Yenicag newspaper were detained at their homes and were being held at a sports hall in Ankara, the daily said on its website, describing the men as critics of the Gulen movement.
Turan Yaldir, a former lawmaker from the Nationalist Movement Party (MHP), was detained in Ankara on similar charges, Yenicag also reported.
"Nationalists will not forget those who are doing this merely to sideline political opponents," Meral Aksener, a senior MHP figure, said in a statement on Twitter. Aksener this year mounted a challenge to the MHP's veteran leader but has faced legal stumbling blocks and could face expulsion from the party.
The chief prosecutor's office in Ankara launched an investigation into 105 suspected leaders of cells in 17 provinces said to be responsible for military personnel in what authorities have dubbed the "Gulenist Terrorist Organisation" (FETO), the state-run Anadolu Agency said.
Authorities have already detained tens of thousands of people over alleged links with Gulen, whose religious movement publicly espouses interfaith dialogue and education, and have made rooting out Gulen's followers their top priority.
The crackdown has alarmed Western allies and rights groups who fear a witch hunt. The body of a teacher who was dismissed last week over suspected Gulenist links was discovered after an apparent suicide, the Dogan news agency said on Wednesday.
Officials have rejected concerns that their actions are too heavy-handed, pointing to the gravity of the coup plot, in which rogue soldiers commandeered fighter jets and tanks and attacked parliament, killing more than 240 people.
Several thousand soldiers have been expelled from the army and more than 100,000 people, including civil servants, bureaucrats, teachers, soldiers and journalists, have lost their jobs for alleged links with Gulen, who has lived in self-imposed exile in the U.S. state of Pennsylvania since 1999.
Turkey wants the cleric extradited.
The ruling AK Party, which has its roots in political Islam and had long collaborated with Gulen's movement, may be using the coup to target other opponents, especially from the secular left, said Veli Agbaba, deputy chairman of the main opposition Republican People's Party (CHP).
"We see many innocent citizens - leftists, social democrats, revolutionaries, Ataturkists and those from different faiths - who have nothing to do with this organization who have opportunistically been suspended or lost their jobs," Agbaba said in a statement.
Ataturkism refers to supporters of the secular principles promoted by Mustafa Kemal Ataturk, who founded the modern Turkish Republic in 1923 on the ashes of the Ottoman Empire.
"Depicting people who have no ties whatsoever to FETO as putschists, replacing them with people from different sects amounts to building a new parallel structure," said Agbaba.
Ozer Sencar, who runs the polling company Metropoll, was also apprehended, according to his Twitter account. Metropoll declined to comment.
The defense ministry said on Wednesday a further 73 members of the air force had been expelled over suspected ties to Gulen.
(Additional reporting by Daren Butler in Istanbul and Gulsen Solaker in Ankara; Writing by Humeyra Pamuk; Editing by Nick Tattersall and Gareth Jones)