MOSCOW - The Russian Foreign Ministry on Tuesday voiced serious concern over the mounting US pressure on Cuba, pledging necessary support for the Caribbean island nation.

"There has been a deliberate effort to ratchet up the atmosphere of confrontation," the ministry said in a statement on its website.

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"Against this backdrop, Russia reaffirms its unwavering solidarity with the Cuban Government and its brotherly people. We firmly condemn attempts to grossly interfere in the domestic affairs of a sovereign state, intimidate it and engage illegal unilateral restrictive measures," it said.

It noted that Cuba today faces unprecedented challenges created by the long-standing trade, economic and financial embargoes imposed by the United States. "For our part, we are providing and will continue to provide Cuba with the necessary support, including material assistance," it said.

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Cuba's national power grid suffered a complete blackout on Monday. For more than two months, no fuel shipments have arrived in Cuba due to the tightening of the oil blockade imposed by the US administration.

US President Donald Trump has threatened that Cuba is going to "fall pretty soon," but his administration will focus on the ongoing war with Iran "right now."