MOSCOW — Prime Minister Vladimir V. Putin of Russia on Friday suggested merging Ukraine’s national energy company with the Russian gas giant Gazprom, a move that, if approved in Kiev, would put Ukraine’s strategic network of gas pipelines under Moscow’s control.

Mr. Putin shocked many — including, apparently, his Ukrainian counterpart — by announcing the proposal at a news conference after talks in the Russian resort city of Sochi. The Ukrainian prime minister, Mykola Azarov, said through a spokesman that the idea of a merger had not come up in their meetings, and that Mr. Putin had “expressed it in an impromptu way.”

Mr. Putin’s idea is an audacious one politically, coming just two months after Ukraine elected a new president, Viktor F. Yanukovich, who vowed to increase cooperation with Russia. Emotions are still raw in Ukraine over a deal Mr. Yanukovich negotiated with Moscow to extend the lease on a Russian naval base on the Crimean Peninsula for 25 years, and a Tuesday vote on the issue in Parliament deteriorated into a melee.

Russia is heavily dependent on Ukrainian pipelines, which carry about 80 percent of its natural gas exports to Europe, and it has long coveted a greater degree of control over them. If the deal were to go through, Gazprom would effectively swallow the Ukrainian company, Naftogaz, said Chris Weafer, chief strategist at UralSib Capital, an investment bank.