EM-SEC Technologies claims to have developed a paint that blocks wireless signals, thereby restricting access to within the building.

Early testing suggests that the technology could be used to safeguard businesses and government facilities from wireless attack.

"The use of EM-SEC coating as an electromagnetic barrier for wireless networks has opened a new realm of possibilities for the future of wireless communications," said Robert Boyd, vice president and director of technology at EM-SEC.

"As hackers, identity thieves and terrorists become more sophisticated, this experiment reduces the threat from electronic eavesdropping and blocks out electromagnetic interference for the protection of electronic data."

The system is a series of water-based shielding products that restrict the passage of airborne radio frequency signals.

A special polymer gives the coating superior adhesion to many plastics and polycarbonates, as well as metals, textiles, wood, drywall and masonry.

The technology was initially developed for the US government and military in shielding operation centres in order to safeguard mission critical information against threats to national and homeland security.

EM-SEC is hoping that its paint can now be utilised by corporate and private companies.

The company claims that a one-time application of the EM-SEC coating creates an "electromagnetic fortress" by preventing airborne hackers from intercepting signals.