Turkish government begun investigating 1,300 personnel at the labour ministry over the failed coup attempt two weeks ago said labour minister, Suleyman Soylu.
Authorities have detained, suspended or placed under investigation tens of thousands of people in state institutions, universities, the police, media and other sectors.
This is only the last of a series of authoritarian actions that took place since the July 15 failed coup.
All the employees under investigation are suspected to have links to Fetullah Gülen, a US-based Islamic cleric accused by Turkish President Erdogan of masterminding the putsch.
Soylu also told Reuters in an interview that the government would soon review its decision to bar civil servants from foreign travel.
The measure was taken last week to prevent alleged Gülen supporters in the civil service from fleeing abroad.
Post-coup crackdown spreads to business sector
Authorities today widened their post-coup crackdown to the business sector, detaining three top tycoons as part of investigations into the activities of US-based preacher Fethullah Gulen.
The probe into coup plotters shifted focus to the financing of Gulen's activities in Turkey, with what appeared to be the first major arrests targeting the business world.
Security forces in the central city of Kayseri detained the chairman of the family-owned Boydak Holding company, Mustafa Boydak, and two other top executives, state-run Anadolu news agency said. He and the two other executives -- Sukru and Halit Boydak -- were detained at their homes.
Efforts were continuing to detain former chairman Haci Boydak as well as Ilyas and Bekir Boydak, for whom warrants have also been issued. Mustafa Boydak is also the head of the chamber of commerce in Kayseri, a fast-growing city dubbed one of the "Anatolian Tigers" for the growth and prosperity it has enjoyed under Erdogan`s rule.
Family-owned holding companies form the backbone of the corporate economy in Turkey, and Boydak Holding has interests in furniture, energy and finance.
It notably owns the prominent Istikbal and Bellona furniture firms.
Prominent journalists appear in Istanbul court
The nationwide crackdown has also sought to wipe out Gulen supporters from the legal system, media, education and civil service. Gulen himself, in self-imposed exile since 1999, strongly denies the charges against him and has called on the United States to resist Ankara`s pressure for his extradition.
Twenty-one journalists also appeared in an Istanbul court today after being rounded up in the sweeping purge, which has seen almost 16,000 people detained.
The scribes, appearing in court, were among dozens of journalists and former newspaper staff issued with arrest warrants earlier this week, to the anger of rights groups.
They included prominent journalists such as the former columnist for the Sabah daily Nazli Ilicak and the commentator Bulent Mumay. Bur Cavusoglu defended the detentions, saying: "It is necessary to make a distinction between those who carried out the coup and who are engaged in real journalism."
Authorities have also ordered the closure of a total of 131 newspapers, TV channels and other media outlets under the three-month state of emergency declared in the wake of the coup. Erdogan, who has dominated the country for 13 years, survived the coup thanks to his supporters who took to the streets to counter rebel troops in tanks and warplanes. The clashes left 270 people dead.
Scale of purge raises alarm
The scale of the crackdown has sparked international alarm, with the European Union (EU) enlargement commissioner implicitly warning the bloc would freeze Turkey's accession talks if it violated the rule of law.
Johannes Hahn said he needed to see "black-and-white facts about how these people are treated". "And if there is even the slightest doubt that the (treatment) is improper, then the consequences will be inevitable," he told German daily Sueddeutsche Zeitung.
Following a shake-up of the military on Thursday after nearly half of its 358 generals were sacked, the top brass of the reshuffled armed forces met Erdogan at his presidential palace in Ankara.
Ninety-nine colonels have been promoted to generals and admirals, although Chief of staff General Hulusi Akar -- who was held hostage during the coup attempt -- stayed in his post along with the heads of the navy, land and air forces.
Turkey insisted its military would keep up the fight against Islamic State (IS) jihadists and other militants, saying the armed forces would emerge stronger from the purge.
"When we weed them (pro-Gulenist elements) out, our army will first of all be more dynamic, cleaner and more effective," foreign minister Mevlut Cavusoglu said, dismissing concerns that the forces would be weakened.