Mr Tully said the high-level decision to arrest the male constable was disappointing and risked damaging morale in the force when it was already at rock bottom.
He questioned whether it was necessary to arrest him over an alleged “policy and procedure” violation when he could instead have been interviewed under caution…
He said: “The thing which disappointed me is around the proportionality of whether it was necessary to arrest the individual. After all, he is a serving police officer.
“Clearly it needs to be resolved, because there are things that we shouldn’t talk about as police officers, and this may be one of those cases.”