JOIN USVint Cerf, a Google vice-president, said the "unbelievable" trend could prevent British businesses from communicating with their customers around the world and in the country.
Cerf said the final tranche of web addresses would be allocated between the organisations that provide them to individual customers in Spring next year, and that they would all be used up "sometime in 2012," the Telegraph reports.
He warned that without the implementation of a new system, "we will run out - there will be address trade and attempts at hijacking".
The bulk of the internet is currently based on a protocol called IPv4. A new version, called IPv6, is already established, but the majority of internet service providers have yet to turn it on.
The two systems cannot talk to each other, so British users of IPv4 will need either new equipment or a software upgrade.
Cerf criticised the shortsighted business decisions that had led to the situation arising, and opened an event to launch a government-backed British organisation called 6UK to encourage the adoption of IPv6.
"If you don't do something about this, the UK will not be able to reach the rest of the world that's on v6," Cerf said.
"It's a business issue that's of relevance to every company that uses the internet to do business. The ISP (internet service provider) will be reduced to selling telephone without a telephone number," he added.