The Commonwealth Ombudsman has launched an investigation into how the AFP and the centre's independent operator handled the violent protests, which saw police firing tear gas and bean-bag bullets at detainees.

The Ombudsman will investigate whether the use of force by police and the centre's independent operator was reasonable. Christmas Island shire president Gordon Thomson says an investigation is needed after a prolonged period of turmoil. Mr Thompson says the riots "bring into question" the mandatory detention policy.

"Clearly those in detention had pretty severe grievances and how those grievances were dealt with needs to be looked at," he said. "What gave rise to those pretty severe demonstrations needs to be looked at in due course."

Immigration Minister Chris Bowen says it is an issue that always needs attention.  The Ombudsman will travel to Christmas Island next week to meet with the island's administrator.