Rostelecom reportedly said it would have a 45% voting stake in the new company, T2 RTK, while Tele2 Russia would have 55%.
Rostelecom said the deal is still under negotiation.
Russia's three major operators – MTS, MegaFon and VimpelCom – control more than 80% of the Russian mobile market. The deal, which has been under discussion for several months, aims to bring greater competition to the market.
If the merger does go ahead, it would create the fourth-largest player in the Russian market with a total of 38 million mobile subscribers.
Tele2 Russia is a former division of Nordic telecoms group Tele2. After failing to secure 3G and 4G licences, the company was sold in April to state-controlled bank VTB and two Russian tycoons.
This month, Rostelecom also announced that it may sell up to $1.4 billion worth of shares in 2014, as it works to reduce its debt.
