Moscow on Thursday denounced Western sanctions against Russia, over the current crisis in Ukraine, as “blackmail, warning of “very serious damage” on the US-Russia relationship.

Moscow on Thursday denounced Western sanctions against Russia, over the current crisis in Ukraine, as “blackmail, warning of “very serious damage” on the US-Russia relationship.

President Barack Obama in sanctions imposed Wednesday took his first direct swipes at the Russian economy's finance, military and energy sectors, further escalating the worst standoff between the Kremlin and the West since the Cold War.

The Russian foreign ministry reacted to sanctions in a furious statement: "We do not intend to tolerate blackmail and reserve the right to take retaliatory measures" against the US.

Russian President Vladimir Putin earlier warned that sanctions would inflict "very serious damage" on the already tattered US-Russia relationship.

"Without any doubt in this case (sanctions) are driving Russian-US relations towards a dead-end, (and) are inflicting very serious damage on them," Putin said while on a visit to Brasilia.

"And I am convinced that this will harm the national long-term interests of the American state, the American people," Putin told reporters.

US sanctions like the ones imposed "have never put anyone on their knees," added Prime Minister Dmitry Medvedev, predicting a "rise of anti-American attitudes".

Moscow gave a milder response to EU sanctions, with the foreign ministry saying it had "submitted to blackmail from the American administration" and should have "its own voice".