Card payment giants Visa and Mastercard announced Saturday they will suspend operations in Russia, the latest major US firms to join the business freeze-out of Moscow.

"Noting the unprecedented nature of the current conflict and the uncertain economic environment," Mastercard said it had "decided to suspend our network services in Russia."

Visa, for its part, said that "effective immediately" it would "work with its clients and partners within Russia to cease all Visa transactions over the coming days."