Around a quarter of mobile network base stations have been taken off-line in the areas worst affected by Hurricane Sandy, the US telecoms regulator has announced.

Citing internal figures from the mobile networks, FCC Chairman Julius Genachowski warned that the communications network is likely to deteriorate further before it improves.

"The storm is not over. Our assumption is that communications outages could get worse before they get better -- particularly for mobile," Genachowski said during a conference call.

A large portion of the remaining towers are running on back-up power supplies as grid electricity supplies are cut across parts of the affected states. While operational at the moment, the back-up power supplies could start running out before grid power is restored.­

About 7 to 8 million people are currently without mains electricity.

The FCC Chairman also recommended keeping voice calls short to reduce power drain on the base stations and where possible sticking to text messaging.

It hasn't been possible to calculate how many people have lost mobile phone service though, as people near a dead base station may be able to make some connections to a more distant working tower.

A small number of emergency 911 call centres also lost power, although most were able to reroute calls to other call centres.