Moscow (CNN) Russian prosecutors in the far eastern city of Vladivostok are investigating the capture of beluga whales and orcas after reports emerged of marine mammals penned inside what some have dubbed a "whale jail," Russian state news agency RIA-Novosti reported Tuesday.

According to local media and the investigative newspaper Novaya Gazeta, more than 100 whales are being held in pens in Srednyaya Bay, near the city of Nakhodka.

RIA-Novosti, citing the Vladivostok environmental prosecutor's office, said 11 orcas (or killer whales ) and several dozen belugas were being kept in cages.

Commercial capture of killer whales is strictly regulated and allowed solely for educational and scientific purposes, RIA-Novosti added.

Packed in cages