Washington ? Federal regulators this week approved the largest ever expansion of wireless Internet access, unanimously backing a controversial plan to allow a new generation of devices to use the empty airwaves between television channels to go online.

Dubbed “Wi-Fi on steroids” by its supporters in the high-tech industry, the plan promises to offer wireless Internet service across America and spur new systems for transmitting video and other data between devices in homes.

The commission’s 5-0 decision – long sought by tech companies including Google Inc. and Microsoft Corp. – came despite staunch opposition from the entertainment industry, which is worried that the Web-surfing devices will interfere with TV broadcasts and wireless microphones.

“The commission chose a path that imperils America’s television reception in order to satisfy the ‘free’ spectrum demands of Google and Microsoft,” said David Donovan, president of the Association for Maximum Service Television, trade group of TV broadcasters.

Though expected to be slower and possibly less secure than commercial broadband services from cable and telephone companies, the new Internet connections will ride on broadcast airwaves capable of carrying signals long distances and easily penetrating trees and walls.

For decades, those government-owned airwaves have been reserved for TV stations. But commissioners approved the plan intended to increase the reach of high-speed Internet access by allowing the use of the spectrum by new laptops, mobile phones and other gadgets with built-in equipment that are expected to hit the market in about two years.

The FCC’s field tests of early prototypes provided by Microsoft and other companies produced mixed results, with some of the devices failing to sense and avoid broadcast signals. Broadcasters said those results show the technology isn’t ready.

But FCC officials said the tests showed that it was possible for devices to use the airwaves without interference.