MOSCOW, January 28. /TASS/. US ambassador to Russia, John Tefft, on Wednesday refused to comment on the progress of a case over three Russian citizens charged with espionage in the US.

"I cannot comment on an ongoing investigation," he wrote on the US embassy page on the Russian VKontakte social network. "But I could possibly recommend you to turn to the full text of the US Department of Justice’s press release that dwells on many of the issues in detail."

On Tuesday, the Russian Foreign Ministry told Washington it was inadmissible to stage secret service provocations against Russian representatives. Moscow demanded that the Russian consular workers in the US be given immediate access to the deputy chief of the Russian Vnesheconombank office, Yevgeny Buryakov, who was arrested in Bronx on Monday.

Like another two workers of Russian diplomatic missions in New York, Buryakov is accused of gathering intelligence data on the possible new US banking sanctions against the Russian banking and financial sector and on the alternative sources of energy being developed by American corporations.

"On the face of it, the Americans haven’t presented any facts to substantiate for their charges," Russian Foreign Ministry’s official spokesman Alexander Lukashevich said.

"We insist on stopping a chain of provocations against Russian representatives unleashed by the US secret services, on granting unconditional access to Yevgeny Buryakov, and on an unambiguous observance of the rights of the Russian citizen and on his release from detention," Lukashevich said.