Saudi Arabia in 2012 sent the United States a written warning naming alleged Boston bomber Tamerlan Tsarnaev as a security threat, a British newspaper reported on Wednesday.

The 2012 warning was a “very specific” one and explicitly named Tamerlan as a suspect, an unnamed Saudi official told the Daily Mail. The message, sent to the US Department of Homeland Security, warned that “something was going to happen in a major US city,” though it didn’t give an exact time or location, he said.

Police believe the 26-year-old Tamerlan and his 19-year-old brother, Dzhokhar, were responsible for the Boston Marathon bombings which killed three and injured over 170 people last month. Tamerlan was killed in a shootout with security forces and Dzhokhar was severely injured before being apprehended.

Saudi authorities also rejected a 2011 request by the older Tsarnaev brother to visit Mecca because of security concerns, the source said.

The report was denied by the US Department of Homeland Security, which told the paper it “has no knowledge of any communication from the Saudi government regarding information on the suspects in the Boston Marathon Bombing prior to the attack.”

The national security council also denied the report, saying it had “no record of such a letter being received” by any American official or office.

The mother of the alleged bombers was added to the terrorism database 18 months before the attacks, the Associated Press reported last week

According to the report, the CIA asked for the elder Boston terror suspect and his mother to be added to a terrorist database in the fall of 2011, after the Russian government contacted the agency with concerns that both had become religious militants, according to officials briefed on the investigation.

About six months earlier, the FBI investigated Tamerlan Tsarnaev and his mother, Zubeidat Tsarnaeva, also at Russia’s request, one of the officials said. The FBI found no ties to terrorism, but the names were added to the list.

The Associated Press contributed to this article.