The websites of several leading companies, including HSBC, Airbnb and British Airways, appear to have been hit by blackouts on Thursday.
A message on BA’s website read: “Service Unavailable – DNS Failed. The server is temporarily unable to respond to your request. Please try again later.
And a post on the Airbnb site said, “This site cannot be reached.”
HSBC’s website had a similar message.
Some of the sites were accessible about half an hour after the first report of the problems, just after 5pm in the UK.
It is not known exactly what caused the problems.
And there are reports that other airlines and major corporations are also affected, as well as 911 service on the east coast of the United States.