MPs (members of parliament) were reportedly told about the hack on Friday night and later told of difficulties in accessing their emails away from the Westminster estate.
A Commons spokeswoman said the lack of email access was not a result of the cyberattack itself but part of the steps being taken to manage the issue.
She said Parliamentary authorities were liaising with the National Cyber Security Center.
The spokeswoman said: "The Houses of Parliament have discovered unauthorised attempts to access parliamentary user accounts.
"We are continuing to investigate this incident and take further measures to secure the computer network..
"We have systems in place to protect member and staff accounts and are taking the necessary steps to protect our systems."
She added: "Parliament has disabled remote access to protect the network."
A number of MPs have confirmed to the BBC they are not able to access their parliamentary email accounts remotely.
It comes just over a month after 48 of England's NHS trusts were hit by a cyberattack.
