Many internet surfers could have been forgiven for thinking the whole internet was broken on Saturday, after a problem with Google left users unable to access any internet sites.

For about an hour, Google was marking all sites that came up in its search results as potentially harmful – the flag that it normally gives to sites that are known to install malicious software on visitors' computers.

Google apologised, and blamed the mistake on a simple typing error in the list of dangerous sites it maintains.

It is not yet clear how badly e-commerce sites will have been affected by the glitch, although predictions have been made that the search engine could have lost up to£2 million in advertising revenue. However, Google’s paid search results were reported as not having been affected.