The Russian anti-monopoly service has begun investigating four dairies over suspicion of collusion.

The Sverdlovsk Office of the Federal Anti-monopoly Service (OFAS) is investigating Irbitsky Milk Plant, Revdinsky Milk Works, Moloko and Pervaya Molochnaya Kompania after they simultaneously increased the prices on dairy products from 1 September.

The case was initiated as the the anti-monopoly agency has been monitoring prices on "socially important goods" during the drought.

"We carry out weekly monitoring of prices for socially-important food products, as a result of which we discovered signs of the 'On Protection of Competition' federal law being violated by milk plants and grain suppliers. Now we will need to find out whether the actions of economic entities were justified or they were speculative," said Sverdlovsk OFAS head Tatiana Koltova.