A spokeswoman for Russia's Foreign Ministry is rejecting U.S. calls for Moscow to withdraw its military specialists from Venezuela and to halt other forms of support for embattled President Nicolas Maduro.

Maria Zakharova said at a briefing Thursday that Russia had sent military help to Venezuela under a bilateral agreement. She questioned the grounds for U.S. Vice President Mike Pence's Wednesday demand for their withdrawal.

"(Was it) on the grounds of international law, on the basis of internal American law or on the basis of some kind of other legal act that nobody knows about?" she said.

Pence's call was "a completely arrogant attempt to dictate to a sovereign state," she said.