Prior to the UK's referendum on leaving the European Union last June, the website for voter registration crashed
. The UK government extended the June 7 deadline for voters to register to vote by a day as a result.
In a report on the lessons to be learned from the EU referendum, the Public Administration and Constitutional Affairs Committee said it "does not rule out the possibility that the crash may have been caused by a DDOS (distributed denial of service attack) using botnets."
Its authors add that they "do not believe that any such interference had any material effect on the outcome of the EU referendum" but say they are "deeply concerned about these allegations about foreign interference."
The Cabinet Office on Wednesday firmly denied that any foreign hacking caused the website to crash.
"We have been very clear about the cause of the website outage in June 2016. It was due to a spike in users just before the registration deadline. There is no evidence to suggest malign intervention," a Cabinet Office spokesperson said.
An unprecedented surge of 525,000 people registered on the day the site crashed, as they tried to submit their details ahead of the cutoff for the June 23 referendum.
The parliamentary committee's report commended the current government for making cyber security a priority but said more needed to be done, including setting up "permanent machinery" to monitor cyber activity around elections and referendums.
"Lessons in respect of the protection and resilience against possible foreign interference in IT systems that are critical for the functioning of the democratic process must extend beyond the technical," it said.
"The US and UK understanding of 'cyber' is predominantly technical and computer-network based. For example, Russia and China use a cognitive approach based on understanding of mass psychology and of how to exploit individuals.
"The implications of this different understanding of cyber-attack, as purely technical or as reaching beyond the digital to influence public opinion, for the interference in elections and referendums are clear."
Russia has been accused of interfering in the US presidential election campaign
last year to the detriment of Democratic candidate Hillary Clinton, an allegation it denies. US President Donald Trump's administration has found itself embroiled in continuing controversy
over ties between his aides and Russia.