President Dmitry Medvedev and his Ukrainian counterpart Viktor Yanukovych held talks in Sochi on Thursday, but the two sides admitted that they are still divided on issues such as gas prices.
In their meeting, Medvedev said that Russian-Ukrainian relations "are developing well," but "this does not mean that there are no problems."
"There are a lot of problems and I suggest we concentrate on them....We'll also discuss gas cooperation, which has traditionally been a complex issue," Medvedev said.
The presidents also discussed the integration processes of Commonwealth of Independent States (CIS) and the border settlement.
In turn, Yanukovych expressed hope that both countries would find a compromise to resolve complex issues, saying "there is a constructive approach to issues."
The Ukrainian government has long urged Russia to review the existing gas pricing formula, but the two sides have not yet reached consensus on the issue.
Ukraine reduced its natural gas supply to European countries by 20.4 percent in 2009 after a price row between Moscow and Kiev halted Russian gas flows to Europe for about two weeks.