Russia declined several FBI requests for more information on Boston Marathon bombing suspect Tamerlan Tsarnaev two years before the deadly 2013 attack, The New York Times reported on Wednesday.
The newspaper cited an unpublished government review. The report could not immediately be verified by NBC News.
The information, including a telephone call in which Tsarnaev and his mother discussed jihad, would potentially have prompted harsher scrutiny of the suspect, according to the paper.
"They found that the Russians did not provide all the information that they had on him back then, and based on everything that was available, the FBI did all that it could," a senior U.S. official familiar with the review told the paper.
Two Chechen brothers, Tamerlan and his younger brother Dzhokhar, are suspected of planting pressure-cooker bombs near the race's finish line last April 15 in an attack that killed three people and wounded more than 260.
Tamerlan died after a gunfight with police while the younger brother is awaiting trial on charges that could lead to the death penalty if he is convicted.
Authored by the inspector general of the Office of Intelligence Community, thew report has not been made public, though lawmakers are to be briefed on it on Thursday, the newspaper said.
Last month, NBC News reported that Russian government warned U.S. authorities that Tamerlan Tsarnaev was a violent radical Islamist more than a year and a half before the April 2013 bombing.
However, authorities missed multiple chances to detain Tsarnaev when he was traveling to and from Dagestan for terror training,. Tsarnaev was supposed to be pulled aside for questioning at JFK airport because he was considered potentially armed and dangerous, but he slipped through undetected because someone had misspelled his last name in a security database.