The ministry also said Moscow hoped they would be "well treated while in custody" and be granted access to Russian lawyers and consulate workers.

Russia's Prime Minister Vladimir Putin (R) meets with former U.S. President Bill Clinton at the Novo-Ogaryovo residence outside Moscow, June 29, 2010. Putin criticised the U.S. arrests of suspects in an alleged Russian spy ring and said on Tuesday he hoped the scandal would not set back improving Russian-U.S. ties. [Xinhua]

Earlier Tuesday spokesman for Russian Foreign Ministry Andrei Nesterenko said the alleged spy reports were groundless, while Russian Foreign Minister Sergei Lavrov said his country awaits explanations from the U.S. side on this incident.

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Lavrov meanwhile said the time of the reports "was selected with a special grace."

Russian President Dmitry Medvedev has just concluded his tour to the United States, during which he and his U.S. counterpart Barack Obama vowed to reset and broaden bilateral ties. U.S. Justice Department said Monday authorities have arrested 10 suspects on charges of spying for Russia. Court documents show they tried to penetrate decision-making circles of the U.S. government. The 11th suspect was detained in Cyprus on Tuesday.

According to a Justice Department statement, they were allegedly carrying out long-term, "deep-cover" assignments in the United States on behalf of the Russian Federation.

Analysts said the case may be an attempt to undermine trust between two countries glimmered during recent summit between U.S. and Russian presidents. But still it is unlikely to have any devastating effect on their bilateral relations.