President Vladimir Putin hinted at last week's NATO summit in Romania that Russia would work to break up Ukraine, should the former Soviet republic join the military alliance, Kommersant reported Monday.

Putin "lost his temper" at the NATO-Russia Council in Bucharest during Friday's discussions of Ukraine's bid to join NATO, Kommersant cited an unidentified foreign delegate to the summit as saying.

"Do you understand, George, that Ukraine is not even a state!" Putin told U.S. President George W. Bush at the closed meeting, the diplomat told Kommersant.

After saying most of Ukraine's territory was "given away" by Russia, Putin said that if Ukraine joined NATO it would cease to exist as a state, the diplomat said.

Putin threatened to encourage the secession of the Black Sea peninsula of Crimea and eastern Ukraine, where anti-NATO and pro-Moscow sentiment is strong, the diplomat said, Kommersant reported.

Kremlin spokesman Dmitry Peskov, who accompanied Putin at the summit, said Monday he did not hear Putin's purported remarks about Ukraine and could not confirm the report.

Putin also offered broader economic cooperation with Georgia's separatist republics of Abkhazia and South Ossetia as Tbilisi sought NATO approval for eventual membership in the alliance.

In a letter sent to the leaders of the breakaway provinces Thursday -- when NATO members were deciding whether to grant Membership Action Plans to Ukraine and Georgia -- Putin said Russia would move beyond symbolic declarations and offer real economic support to Abkhazia and South Ossetia, the Foreign Ministry said in a statement.

Just days before the summit, Moscow officially lifted long-standing embargoes on trade, transportation and financial transactions with Abkhazia.

France, Germany and several other NATO members opposed putting Ukraine and Georgia on the path toward NATO to avoid provoking Russia, and the alliance postponed consideration of their eventual membership.