Anti-corruption officers swooped on Edmonton police station in north London yesterday, turning it into a crime scene, following an operation lasting several weeks.
Those under investigation are mainly Pcs attached to the local crime squad. Two more have been placed on restricted duties.
The investigation concerns the alleged taking of items from the property stores at the station - which hold items such as iPods recovered from robbers.
Listening probes and secret cameras are said to have been set up at the station to try and catch suspect officers.
The operation follows the recent jailing of a female civilian property officer at Edmonton who was caught setting fire to records.
The Met said there were no arrests.
A spokeswoman said: "Nine officers were today suspended and two also put on restricted duties following a pro-active investigation by the anti-corruption team.
"The investigation centres on the alleged mishandling of property. All the officers are based on Enfield borough. There have been no arrests and inquiries continue."
The spokeswoman added: "The Metropolitan Police demands the highest levels of honesty and integrity from its officers and staff. All allegations of malpractice are taken extremely seriously and are investigated swiftly and thoroughly.
"This investigation will not affect day-to-day policing in the area."