Police detained four executives from Boydak Holding, a prominent business conglomerate, as part of an inquiry into the corporation's ties to the controversial Gülen Movement and allegations of financing the movement's terror activities.

The company's CEO Memduh Boydak, chairman of the board Hacı Boydak, board member Erol Boydak and senior executive Murat Bozdağ were detained in the early hours of Friday by the police's organized crime unit in the central city of Kayseri where the corporation's headquarters are located. Hacı and Memduh Boydak are accused of membership in the Gülenist Terror Organization (FETÖ) and funding Gülenists, while two other men were detained for "terror propaganda via social media" for posts supportive of FETÖ.

Police squads searched the homes and offices of the detainees while the financial crimes unit examined computers at the company headquarters for suspicious money transactions.

Memduh Boydak was interrogated by prosecutors last year over a case of misuse of lands allocated to the company by local authorities – a charge stemming from the unauthorized building of a mansion in an area designated as a forest - as well as insulting President Recep Tayyip Erdoğan. He was also detained in another corruption investigation.

FETÖ, an official name given to some supporters of the Gülen Movement headed by U.S-based retired imam Fethullah Gülen, according to prosecutors, faces charges of terrorism for two attempts to overthrow the government in 2013. Since then, a string of investigations were launched against the group and found infiltrators of FETÖ within the police, judiciary and bureaucracy involved in a set of crimes ranging from illegal wiretapping to orchestrating sham trials to imprison the movement's critics.

Boydak Holding, famous for its furniture brands İstikbal and Bellona, owns 41 subsidiaries in various sectors ranging from furniture to cable production, energy and textile. With nearly 14,000 employees and a yearly turnover of about TL 6.9 billion ($2.3 billion) –according to 2015 figures -, it is among the country's largest industrial companies.

Authorities have turned their attention to companies suspected of financing the activities of the Gülenists following a purge of Gülenist infiltrators in 2014 and the following years. Koza İpek Group, another large conglomerate with interests in media and energy, were the target of a probe against Gülenists and a court assigned trustees to run the company while an investigation is underway on charges that the conglomerate's chairman, Akın İpek, secretly funneled a large amount of cash to FETÖ.