According to Josip Pojavnik, deputy warden of Zenica prison, prison guards grew suspicious when they saw "four prisoners visibly intoxicated shortly after the pigeon landed on a prison window."
It is believed that the drugs were stuffed into tiny bags and attached to the pigeon's legs.
"We suspect that the pigeon carried the drugs from Tuzla, a town around 70 kilometres more than 40 miles northeast of Zenica in central Bosnia," Telegraph quoted Pojavnik, as saying
The pigeon is behind bars while police investigates who might have loaded with drugs.
"We do not know what to do with the pigeon, but for the time being it will remain behind bars," said Pojavnik.
The prison officials are now considering to closing down a prisoner pigeon-breeding project established in a ward of the jail as part of a rehabilitation programme.