The remaining slices of the internet were shared out this week and now growth will come at a cost, says internet New Zealand.

The internet Address and Naming Agency allocated the last blocks of internet addresses on Tuesday, with three out of the eight remaining blocks going to the Asia Pacific region.

These internet addresses are the unique number given to every device that accesses the internet whether it is a laptop, a printer or a mobile phone.

Websites also have an individual number, but this is translated into the words (eg www.nzherald.co.nz) which internet users type into their browsers.

The version of these numerical addresses, which 99 per cent of the world's internet devices use, is called IPv4.

There are 4.3 billion unique IPv4 addresses worldwide and 16.8 million in each of the blocks the agency gave out.

Once these are used up, devices will have to be given an address from an old device (which will then not be able to access the internet) or be given a new (and longer) IPv6 address.

There are 340 trillion unique IPv6 addresses which can be given to individual devices.

However, as it stands, the 4.3 billion IPv4 devices will be unable to connect to websites through IPv6.

Internet New Zealand chief executive Vikram Kumar said that while users would notice no difference in the short term, the transition between the two versions must be managed.

He said New Zealand needed to save some of the remaining IPv4 addresses allocated to the Asia Pacific region before they were sucked up by big-growth nations such as China.

"It we don't handle it well in the next few months and years, it will cause a major problem and the problem will grow," Kumarsaid.

"This essentially breaks down the fundamental of the internet - that anyone can talk to anyone. Increasingly, if I am doing business with India or China and they only have an IPv6 address and I only have an IPv4 address it will be hard to connect," he said.

While there would be some "technology smarts" by those looking to extend the life of their IPv4 addresses, Kumar said this ignored the reality that the world was shifting to IPv6.

While this transition was taking place, he said, websites should be "dual-stacked" and hosted on both IPv4 and IPv6 to ensure connection.