(Adds French foreign minister's comments)
MOSCOW, March 19 (Reuters) - Russia accused Western states of violating a pledge to respect Ukraine's sovereignty and political independence under a 1994 security assurance agreement, saying they had "indulged a coup d'etat" that ousted President Viktor Yanukovich last month.
The Foreign Ministry said actions by the United States and European Union ran counter to assurances granted by the United States, Britain and Russia in exchange for Ukraine's commitment to give up its nuclear arsenal after the Soviet collapse.
French Foreign Minister Laurent Fabius said it was Russia that violated the 1994 Budapest Memorandum on Security Assurances, which also committed the signing countries to respect Ukraine's existing borders.
He said Russia's annexation of Crimea, which followed the ouster of Yanukovich after a three-month standoff between police and mostly pro-Western protesters, could undermine efforts to prevent the spread of nuclear arms.
Speaking alongside his Brazilian counterpart, Fabius said that "one of the countries that agreed to guarantee (Ukraine's) integrity, Russia, has on the contrary violated it.
"That's serious. Why? Because it could mean that countries that have nuclear weapons won't want to give them up, while countries that don't have them may want to acquire them because that will be the only way to protect their territorial integrity." (additional reporting by John Irish in Paris, Writing by Steve Gutterman, editing by Elizabeth Piper)