Russia voiced outrage Friday at charges in the United States against 49 current and former Russian diplomats and their wives over a $1.5 million fraud, saying it could not understand why the U.S. had gone public with the allegations.

Deputy Foreign Minister Sergei Ryabkov said in a statement to Russian news agencies that Moscow had many claims against the behavior of U.S. diplomats in Moscow but had preferred not to bring them into the public sphere.

"We categorically reject the charges against the staff of Russian diplomatic institutions in the United States," he was quoted as saying by the ITAR-TASS news agency, saying it was "illegal" for diplomats to have been watched by the authorities in this way.

"If the American authorities have claims against our citizens... they should have been made first through diplomatic channels. This is no more than cheap PR and an attempt to fulfill an order by Russophobes in the U.S.," he added.

Ryabkov hinted that Russia had many allegations it could lay against American diplomatic staff if it so desired but said Moscow had preferred stay quiet.

"We have many claims against how American embassy staff work and act. But we do not want to go down the path of a rhetorical war of mutual accusations," he said.

The scandal risks causing a new crisis in U.S.-Russia relations which have already been scarred by Russia's decision to grant asylum to U.S. intelligence leaker Edward Snowden and a host of other issues.