The Boston Marathon bombings could have been prevented if US officials had followed through on Russian intelligence, a senior Moscow official has said.
Valentina Matvienko, the speaker of Russia's senate, said: "The Russian side warned the American side about the Tsarnaev brothers, but this information was not taken seriously by the American side, which is what led to that tragedy," the Interfax news agency reported.
Ms Matvienko is the long-time governor of Russian president Vladimir Putin's home town of St Petersburg, is considered a close Kremlin confidante and was named Russia's most powerful woman this year by Ekho Moskvy radio.
"Today the world has to deal with common global challenges and international terrorism, as well as crime, and the co-operation of intelligence services becomes extremely significant for this issue," she added.
Officials had previously backed Mr Putin's statement that Russia had no information that could have prevented the attacks.
Security officials told a Congressional delegation to Russia last week that they believed that if Russia and the US had worked together more closely, the bombings might have been averted, Representative William Keating said.
He added that a top Russian counter-intelligence official told the delegation that "had we had the same level of communication as we do now, the Boston bombing may never have happened".
It was unclear, however, whether the Russians said they had enough information to prevent the attack at the time. Representative Steve Cohen said that Russian officials seemed not to have known that Tamerlan Tsarnaev went to Dagestan, a restive Caucasus province racked by an insurgency, for six months last year when he returned to Russia.