A pod of dolphins has escaped from a recreational facility in the Japanese town of Taiji, known for its annual controversial hunts.

Staffers from the Dolphine Base Center discovered nets dividing the pools from the ocean had been slashed, allowing four dolphins to get out.

An official blog  said the dolphins had “stayed close to their pen” and that three returned on their own accord.

Local police say they do not yet know who was behind the incident.

The bottlenose dolphins were estimated to be between three to five years old. They were being trained in the seaside pens having been held there for more than six months.