ISTANBUL (Reuters) – Turkish authorities detained 29 inspectors on Friday from the BDDK banking watchdog for “irregular inspections,” broadcaster NTV and other media reported, in what appeared to be the latest round-up related to the failed July 15 coup.

Turkey has so far detained around 40,000 people in its investigation following the attempted putsch, which it blames on followers of U.S.-based Muslim cleric Fethullah Gulen, who has denied the charge.

Around half of those detained have been formally arrested for links to the coup attempt when rogue troops attacked state institutions in a bid to overthrow the government.

The investigation has also lead to a sweeping purge of the military, civil service, police, and judiciary, with nearly 80,000 removed from public duty. The scope of the crackdown has unnerved Turkey’s NATO allies, who fear President Tayyip Erdogan is using the purges to stifle dissent.

The banking investigators were detained on suspicion of making “irregular investigations” into the account of a government-related foundation and those of business people, including targets close to Erdogan, NTV said.

A spokesman for the BDDK, which regulates Turkey’s banking sector, was not immediately available for comment.

Erdogan has long accused Gulen, who has lived in self-imposed exile in Pennsylvania since 1999, of running a “parallel network” inside government institutions and the military. Gulen has denied that charge and condemned the coup attempt.

Gulen’s organisation, which has followers across society, helped Erdogan in the first years after his AK Party was elected in 2002. But the two later fell out after police and prosecutors seen as sympathetic to the cleric opened a corruption investigation into Erdogan’s inner circle in 2013.

(Reporting by Ebru Tuncay and Tuvan Gumrukcu; Writing by David Dolan; editing by Patrick Markey)