The Kommersant daily said it was probable that the suspected agent Ryan Fogle was looking for information on the Tsarnaev brothers who are alleged to have carried out the marathon bombings.
It linked the agent's capture, which threatens to further stress ties between Washington and Moscow, to a trip that a US delegation made to Dagestan in April in coordination with the Russian authorities to investigate the blasts.
"It is likely that during the trip in April the US side obtained the phone numbers of (Russian) Federal Security Service (FSB) agents," said Kommersant, which is known for its contacts in the security service and foreign ministry.
"Clearly, they then decided to use it to have personal contacts with anti-terror agents, given that the exchange of information in the form of question and answers between special services is not always quick and smooth," it said.
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The FSB has already announced that Fogle was apprehended while seeking to recruit a Russian security service agent while looking for information on the Northern Caucasus.
Kommersant noted that the payment allegedly promised -- an advance of $100,000 rising up to $1 million -- was unusually high.
"The CIA needed the (Russian) anti-terror agent after the terror attack in the Boston marathon," it said.