A Halifax undercover detective has been suspended with pay while under investigation for theft and breach of trust.

The officer is Const. Gary Basso, who once received a commendation from then-police chief Frank Beazley, CBC has learned.

Halifax police confirmed the officer under investigation is an 11-year veteran of the force.

The Serious Incident Response Team has taken over the investigation of "significant" allegations, director Ron MacDonald said Thursday.

Ron MacDonald, director of the Serious Incident Response Team, says an undercover detective with the Halifax Regional Police is under investigation. (CBC)

"Police officers have certain duties that are core to their job and if we see a breach of a core obligation of a police officer in a significant way, that really goes to the very core of what it is police do," MacDonald said.

"The allegation is of that nature so that's why I term it significant."

Basso investigated major drug trafficking cases.

In one recent prominent bust, Basso seized cocaine and marijuana in Bedford and Halifax, as well as $110,000 in cash. The charges in the case have been stayed. Prosecutors have a year to lay charges again.

Basso's cases have been reassigned to other officers in his absence.

Alleged theft happened inside police headquarters

The allegations stem from March 2015 and from within police headquarters in Halifax, MacDonald said.

The alleged theft could include police evidence, MacDonald said, as he declined to confirm what exactly was stolen.

"The value of the material probably isn't as important as the nature of the material that was taken. However, I would estimate the value to be under $5,000," MacDonald said.

More than a dozen police officers provided statements, he said.