By Daren Butler

ISTANBUL (Reuters) - Turkey ordered dozens of businessmen and academics, arrested for alleged links to the U.S.-based cleric blamed for the failed July 15 coup, to remain in jail pending trial on Thursday, Turkish media said.

Arrest warrants were also issued for around 50 military officers, adding to the tens of thousands of people already detained over links to the cleric, Fethullah Gulen, who denies any involvement in the attempted putsch. The crackdown has alarmed Western allies and rights groups.

Officials have rejected concerns that their actions are too heavy-handed, pointing to the gravity of the coup plot, where rogue soldiers commandeered fighter jets and tanks and attacked parliament, killing more than 240 people.

Among 27 businessmen formally arrested on Thursday pending trial was leading clothing maker and retailer Omer Faruk Kavurmaci, the son-in-law of Istanbul's mayor, Kadir Topbas, state-run Anadolu Agency reported.

Also held was Faruk Gullu, owner of a chain of shops selling baklava, a traditional sweet Turkish pastry. He is accused of belonging to what Ankara terms the "Gulenist Terrorist Organisation" (FETO), Anadolu said.

They were among 80 suspects detained three weeks ago as part of the investigation. Gullu's brother Nejat, who runs a rival chain of baklava shops, was among dozens who were released subject to judicial monitoring, meaning they could still face prosecution, the agency said.

In the southeastern province of Malatya, 21 university academics were jailed pending trial, accused of being members of FETO, the Dogan news agency reported.

Separately, Istanbul prosecutors issued detention orders for six generals, 43 other officers and some civilians in a police operation extending across 15 provinces, Anadolu reported. Four of them have been detained so far, the agency said.

"CRISIS CENTERS"

On Wednesday, police detained three journalists, a politician and a pollster and issued arrest warrants for another 105 people over suspected links to Gulen.

Opposition politicians said the latest wave of arrests may target government critics with no clear links to the religious movement led by Gulen, whom Turkey wants extradited.

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 Pennsylvania since 1999.

President Tayyip Erdogan addressed concern about the handling of the purge in comments published on Wednesday, acknowledging that the wrong people may sometimes be targeted and that media speculation about them may be misleading.

"They make comments (on TV) accusing people who have nothing to do with this business. But that person is stuck with that label. Such things are not right," he told reporters, according to Hurriyet newspaper.

Prime Minister Binali Yildirim said "crisis centers" would be set up across Turkey to handle the claims of those who feel they have been targeted unfairly by the coup investigation.

"If a mistake is made, if there is anything contrary to justice and the law, it will be reviewed after operations are completed and mistakes will be corrected," he said in a speech.

(Writing by Daren Butler; Editing by Larry King and Robin Pomeroy)