Late last night, Varna Mayor Blagomir Kotsev was escorted to Sofia and is currently in the National Investigation Service.
The investigation is being conducted by the Anti-Corruption Commission under the leadership of the Sofia City Prosecutor's Office, BTV reported.
Kotsev's detention order will be reviewed on Friday.
There are four defendants in total - the mayor, two municipal councilors from the PP, as well as Ivaylo Marinov, who is a partner in a catering company.