Hackers have launched a cyber attack on the British parliament in a bid to break into the email accounts of lawmakers and and their staff, a spokesman confirmed Saturday.

Users of the Westminster system have been unable to access their accounts remotely due to defensive measures put in place by parliamentary authorities to deal with the hack.

The National Cyber Security Centre (NCSC) and the National Crime Agency are probing the incident, which comes after reports that passwords for ministers and lawmakers were being sold online by hackers.

The parliamentary spokesman declined to give information about whether and what kind of information has been stolen.

An email sent by parliamentary authorities to those impacted said that after "unusual activity" was noticed, "closer investigation by our team confirmed that hackers were carrying out a sustained and determined attack."

Speaking at Glastonbury Festival, Labour leader Jeremy Corbyn said the attack showed "just how vulnerable we are to cyber attacks and our cyber security."

"We need to be investing in cyber protection, it is a huge issue. We all rely on computers, we all rely on emails, we all rely on digital records - you wouldn't leave your building without importing documents under lock and key. A computer is just the same," he said.