The National Republican Congressional Committee - the election arm of Republicans in the U.S. House - reported on Wednesday that it was the target of a 'cyber intrusion' during the 2018 election campaign, with reports indicating those responsible may have been located outside the United States.

"The NRCC can confirm that it was the victim of a cyber intrusion by an unknown entity," the group said in a written statement sent to reporters.

The story was first reported by Politico, which said the GOP believed a foreign entity was responsible.

The NRCC said it notified the FBI, and launched an internal investigation.

"To protect the integrity of that investigation, the NRCC will offer no further comment on the incident," the statement read.

The story line drew immediate parallels to hacks during the 2016 campaign against Democrats - except the emails and information reportedly accessed does not seem to have been made public.

"This NRCC hack shows cyber security is not a partisan issue," said Rep. Ted Lieu (D-CA).