Story highlights US officials believe Russian hackers have targeted news organizations

The breaches are thought to be part of a larger effort aimed at the US political system

(CNN) Hackers thought to be working for Russian intelligence have carried out a series of cyber breaches targeting reporters at The New York Times and other US news organizations, according to US officials briefed on the matter.

The intrusions, detected in recent months, are under investigation by the FBI and other US security agencies. Investigators so far believe that Russian intelligence is likely behind the attacks and that Russian hackers are targeting news organizations as part of a broader series of hacks that also have focused on Democratic Party organizations, the officials said.

The Times said email services for employees are outsourced to Google. CNN requested comment from Google but didn't receive comment. The FBI declined to comment.

Times spokeswoman Eileen Murphy said the company had seen "no evidence" that any breaches had occurred of the Times's internal systems. CNN's report didn't say that the Times internal systems were breached, but that reporters were targeted.

"We are constantly monitoring our systems with the latest available intelligence and tools. We have seen no evidence that any of our internal systems, including our systems in the Moscow bureau, have been breached or compromised," Murphy said.

Read More