Authorities in Russia on Monday announced that they have discovered a diamond theft gang that has stolen at least $3 million worth of diamonds. 

The gang had been carrying out its operations in the sorting and grading department of Alrosa, the country's largest rough diamond producer, Reuters reported. 

"Alrosa completely confirms information from Russia's FSB (security service) about the interception of an extensive scheme to steal rough diamonds in the company's United Selling Organization," the company said in a statement.  

Three suspects were detained, with one of them, Elena Kanunnikova, being an employee of Alrosa.The three were caught last week attempting to steal a batch of diamonds worth $340,000. Stolen jewelry was also found, including 30 diamond crusted watches along with wads of $100 bills.   

Alrosa, which is partially owned by the Russian government, competes with UK-based diamond mining and retail company De Beers. 

On Monday, figures from Alrosa showed that the company has sold $700 million worth of diamonds less in the first five months of the year as in the same period of last year. In May alone, the company sold $266 million worth of rough and unpolished diamonds. The diamond industry currently faces a supply glut.