KYIV, Dec. 14 – Ukraine and Russia have failed to reach an agreement on natural gas transit at the latest round of talks on Friday, but will continue negotiations, a senior Naftogaz official said Saturday.

The developments elevate the risk dramatically that the parties will not have the agreement by the end of December, when the current 10-year deal is set to expire.

"It is too early to talk about an approved option, but we are taking the most constructive position. Active work continues," Naftogaz executive director Yuriy Vitrenko wrote on Facebook.