A cyber attack on Britain's Talktalk Telecom Group PLC broadband affected "a small number of customer routers" on Thursday, the company said in a statement.
"Along with other Internet Service Providers in the UK and abroad, we are taking steps to review the potential impacts of the Mirai worm", Talktalk said, adding it has put additional controls in place.
Mirai is a malicious software which in October cut off access to some of the world's best known websites, including Twitter and Spotify.
A cyber attack affecting some types of routers hit around 100,000 of Britain's Post Office broadband customers on Sunday, Post Office said in a statement on Thursday.
The company added, "although this did result in service problems... no personal data or devices have been compromised. We have identified the source of the problem and implemented a resolution."
On Tuesday the German government and commercial security experts said hundreds of thousands of Deutsche Telekom AG customers suffered internet outages as a result of a worldwide attempt to hijack routing devices.
(Reporting by Kanishka Singh and Rama Venkat Raman in Bengaluru; Editing by Alexandra Hudson and Grant McCool)