A growing number of Russian regional officials are facing criminal investigations as authorities intensify a crackdown on alleged corruption across regional governments.

At least 28 high-ranking officials, including regional ministers, vice governors and their deputies, have come under investigation on charges ranging from bribery and fraud to embezzlement and abuse of office since the start of the year, according to data compiled by the independent Telegram news channel ChTD.

A large number of these investigations center on the construction of defensive fortifications in Russian regions bordering Ukraine.

The arrests continued this week, with Maxim Yegorov, the former governor of the Tambov region who stepped down last November, arrested Wednesday on suspicion of accepting bribes.

The same day, investigators in the Chelyabinsk region arrested Eldar Belousov, the regional minister for state property management; Roman Menzhinsky, chief of staff to the governor; and former Vice Governor Alexander Bogashov.

All three face criminal charges of abuse of official authority carried out by a group for personal gain, a crime punishable by up to 10 years in prison.