Sir Tim Berners-Lee said that such an operation would require co-ordinated action from the world's governments as the net cannot be taken down from a single location.
"The way the internet is designed is very much as a decentralised system," said the computer scientist.
"At the moment, because countries connect to each other in lots of different ways, there is no one 'off' switch, there is no central place where you can turn it off."
He added: "In order to be able to turn the whole thing off or really block, suppress one particular idea, then the countries and governments would have to get together and agree and co-ordinate and turn it from a decentralised system to being a centralised system.
"And if that does happen it is really important that everybody fights against that sort of direction."
Berners-Lee, who heads up the World Wide Web Consortium, launched the Web on Christmas day in 1990 with the help of CERN student Robert Cailliau.