A guard and a detainee have been injured in an incident at Tasmania's Pontville Detention Centre overnight involving 50 people.

The Department of Immigration has confirmed one officer and one detainee were injured during the disturbance at Pontville about 10pm.

The incident involved two groups of young men, who were later separated.

The detainee was treated on site but the condition of the officer has not been confirmed.

The union representing Pontville officers says its members have not raised issues about their security in the past.

The union's Helen Gibbons says she is surprised by the incident.

"This is a centre that has a reputation for being the best-run centre in Australia," she said.

A spokeswoman for community group Tasmanian Asylum Seeker Support, Emily Conolon, says incidents are to be expected when teenagers are detained.

"To me it only reinforces the need that these boys need to be living in a family-like environment out in the community."

Another refugee advocate Ian Rintoul agrees Pontville has a good reputation compared to other detention facilities.

"No matter how well a detention centre is run or the level of community involvement, a detention centre is a detention centre and when people are locked inside a place like Pontville there's all kinds of tensions and strains."

The department says the incident is being investigated and the facility is now calm.