Russian operatives compromised systems in 7 states in 2016 US elections: Report

US intelligence had evidence that voter registration systems or websites in seven states - Alaska, Arizona, California, Illinois, Texas, Florida and Wisconsin - were compromised by Russian-backed operatives before the 2016 election but never told the states, NBC News reported on Tuesday.

The network, citing unnamed US officials, said that top-secret intelligence requested by President Barack Obama in his last weeks in office synthesised months of work and concluded there were seven states where Russian operatives had compromised websites or databases.

Only Arizona and Illinois had previously been identified as states that experienced some level of intrusion into their election systems.

While officials in Washington told several of the states ahead of the elections that foreign entities were probing their systems, none were told the Russian government was behind it, NBC News reported, citing unnamed state officials.

The Trump administration contacted election officials in all 50 states in September 2017 to advise them whether or not their systems had been targeted. It told them 21 states had been targeted and some had been breached, NBC News reported.

Six of the seven states that were breached continued to deny it, citing their own cyber investigations, NBC News reported. It said the systems in the seven states were compromised in a variety of ways, including entry into state websites and penetration of voter registration databases.

All of the state and federal officials agreed that no votes were changed and no voters were removed from voter roles as a result of the activity by Russian operatives, NBC News reported.

Department of Homeland Security officials and states have frequently disagreed on the extent of Russian intrusion into their systems during the 2016 election cycle.

A spokesman for the Department of Homeland Security did not immediately respond to a Reuters request for comment.

While DHS acknowledges that 21 states experienced a level of initial probing by suspected Russian hackers, it has only previously said publicly that a small subset of those states witnessed any actual compromise of their networks.