Two of the sources linked the increased Russian interest directly with reported Turkish plans to crack down on the transit of sanctioned goods.
Some Russian firms have sought to establish long-term sanction-busting partnerships, the sources said.
Under Russian law, it is an offence to comply with the Western sanctions and sanctions-busting has become a profitable boom industry for some entrepreneurs.
Ankara also said it would not allow Western sanctions to be violated in or via Turkey and was taking steps to prevent this.
Kazakh exports to Russia rose by a quarter to $8.8 billion last year and sales of some items surged.