The war of words between Moscow and the West over Ukraine has continued this weekend.
On Saturday US Vice-President Joe Biden warned Russia not to use its energy resources as a political weapon.
“I have no doubt Russia will and should remain a major source of energy supply for Europe and the world,” he told an energy summit in Turkey.
Russia and Ukraine reached a temporary pricing deal last month after Moscow cut gas supplies to its neighbour.
On a visit to Kyiv on Friday, Biden accused Russia of a “flagrant violation” of international law, and urged Moscow to pull soldiers out of eastern Ukraine.
On Saturday Russia’s foreign minister hit back, accusing the West of using sanctions to seek a change of regime in Moscow, not just a change of policy.
Sergei Lavrov said Western countries had flouted their own principles about democratic changes of power by supporting extremists, and using coercive methods.
He cited calls for sanctions aimed at destroying the economy and inciting protests.
As pro-Russian separatists continue battling forces loyal to Kyiv in eastern Ukraine, Moscow’s stance seems to be hardening.
It denies arming rebels or sending soldiers into Ukraine.
But vast convoys have been seen moving through separatist territory.
NATO accuses Moscow of pouring troops and military hardware across the border.