The Russian government refused to provide the FBI with information about one of the Boston bombing suspects two years before last year's attack, The New York Times reported late Wednesday.

An inspector general’s report found Russian officials declined multiple requests by the FBI to obtain additional information about Tamerlan Tsarnaev, the older brother who died in a shootout with police.

“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 American official briefed on the review told the Times.

In 2011, Russian officials told the FBI that Tsarnaev “was a follower of radical Islam and a strong believer” who “had changed drastically since 2010 as he prepared to leave the United States for travel to the country’s region to join unspecified underground groups.” 

FBI officials had already conducted an initial investigation into Tsarnaev’s background.

Agents assessed Tsarnaev’s criminal and educational records, and his Internet search history, the report said. Agents also interviewed him, his parents and people at his school.

After the initial probe, U.S. officials repeatedly requested more information on Tsarnaev, but Russian officials declined to share additional intelligence.

The inspector general of the Intelligence Community — which oversees 17 agencies — compiled the report, and it hasn’t been publicly released. 

“Had they known what the Russians knew they probably would have been able to do more under our investigative guidelines, but would they have uncovered the plot? That’s very hard to say,” one senior official told the Times.

The report comes nearly a year after the April 15 bombing when Tsarnaev and his brother, Dzhokhar Tsarnaev, set off pressure cooker bombs at the Boston Marathon’s finish line.

The bombing left three people dead and more than 260 wounded. The younger Tsarnaev, who was captured in the days after the bombing, could face the death penalty.