Russia condemned the US military action in Venezuela on Saturday and demanded "immediate" clarification about what happened to Venezuelan leader Nicolas Maduro, who US President Donald Trump said was captured by US forces.

Venezuela is Russia's most important ally in South America, though the Kremlin has stopped short of offering assistance to Caracas in the event of a conflict with the US.

Early Saturday, "the United States committed an act of armed aggression against Venezuela. This is deeply concerning and condemnable," the Russian foreign ministry said in a statement.

"The pretexts used to justify such actions are untenable. Ideological hostility has triumphed over businesslike pragmatism," it added.

In a later statement, the ministry said it was "extremely alarmed by reports that Venezuelan President Nicolas Maduro and his wife were forcibly removed from the country as a result of today's US aggression".

"We call for an immediate clarification of the situation," it added.

Russia reaffirmed its support for Maduro last month and was one of only several countries to congratulate the embattled Venezuelan leader following his disputed re-election in 2024.