Turkish police issued 187 arrest warrants against businessmen and ordered their assets seized as authorities raided some 200 homes and workplaces on Thursday, a sign that the investigation into last month’s failed military coup shifted towards the business community.

President Recep Tayyip Erdogan has vowed to choke off businesses linked to the U.S.-based Muslim cleric Fethullah Gulen, whom he accuses of being the mastermind behind the July 15 coup attempt, describing his schools, firms and charities as “nests of terrorism.”

Police from a financial crimes unit launched dawn raids in Istanbul and 17 other provinces targeting businesses suspected of backing Gulen’s movement, the private Dogan news agency reported.

An undisclosed number of people were detained at their homes and offices, the state-run Anadolu Agency said.

Gulen, formerly close to Erdogan but now living in self-imposed exile in Pennsylvania, has denounced the coup attempt, and denied any responsibility for it.

Dogan said prominent businessmen were among the suspects being sought by police on suspicion of “membership in a terror organization” and “providing financial support to a terror organization.”

Turkey classified Gulen’s movement as a terrorist network in July 2015.

Separately, a court ordered that 187 suspects’ assets be seized, according to Anadolu.

Earlier this week, police searched the offices of a nationwide retail chain and a healthcare and technology company.

Prime Minister Binali Yildirim said on Wednesday that 40,029 people had been detained since the coup attempt, and about half had been formally arrested pending charges.

He also said 4,262 companies and institutions with links to Gulen had been shut, and that 79,900 people had been removed from public duty in purges of the military, police, civil service and judiciary.

The European Union and the United States have expressed concern about the scale of the crackdown, and human rights groups have said a lack of due process will ensnare innocent people who had no role in the abortive coup.

Turkish officials say they have to act fast to prevent further attempts to destabilize the government from within the bureaucracy and the business community.

A faction of the military attempted to seize power on July 15, killing some 240 people, mostly civilians, and wounding 2,000. About 100 people backing the coup were also killed, according to official estimates.