Two police officers were detained outside a bank in central Moscow as they were preparing to carry out an armed robbery, investigators said.

The officers and two suspected accomplices were detained outside a VTB branch on Bolshaya Tatarskaya Ulitsa on Wednesday as they were waiting to ambush cash couriers exiting the branch, the Investigative Committee said in a statement.

The two civilian suspects are both natives of the rebel Georgian region of Abkhazia, investigators said.

Police had been tracking the group in connection with a series of robberies of Moscow cash couriers last year, city police spokesman Viktor Biryukov told Interfax.

One of the police officers had been implicated in an illegal weapons-possession case last month, while the other was a suspect in a drug-trafficking case and was in possession of narcotics when he was detained Wednesday, the Investigative Committee said.

The country's police force has been widely criticized for hiring officers involved in criminal activities.  

Yury Draguntsov, head of the Interior Ministry's internal affairs department, told government daily Rossiiskaya Gazeta in an interview published Thursday that his department is investigating several officers with the Moscow police's central district branch for purported economic crimes.

"A senior officer investigating economic crimes for the [central district] branch was detained while extorting a bribe of $50,000 from a businessman," Draguntsov told the newspaper.

Draguntsov said he was unhappy with the media's coverage of cases of police corruption, saying news outlets ignore the success of his department in catching corrupt officers.