Lloyds, Halifax and Bank of Scotland customers are unable to use online banking.
Mobile banking through the smartphone apps was also unavailable for most people.
All three banks, which are part of Lloyds Banking Group, tweeted to say they were working to fix the problems and apologised to customers.
The message said: “We know our customers are having issues with internet and mobile banking.
“We’re sorry about this and we’re working to have it back to normal soon.”
The Down Detector website reported that thousands of users were unable to access online and mobile banking from around 4am.
more recommended stories
Louis Jr Tshakoane’s Forex Book Now a Best-Seller!World renowned Prophetic Forex Trader Louis.
Tesco announces 4,500 job cuts across stores nationwideTesco has announced is is to.
Vauxhall owner PSA ‘could move Astra production from UK’The chief executive of Vauxhall-owner PSA.
United States firms rethink China presence because of trade warMost US businesses in China are.
South Africa oil discovery could be a game-changer and major boost for the economySouth Africa’s offshore has just yielded.
Despite heavy discounting Boxing Day sales ‘attracting fewer shoppers’The number of people heading to.