Campaign group HDforAll is applying pressure to UK regulator Ofcom in an attempt to ensure high-definition TV for Freeview users in the UK.

Ofcom has announced plans to auction off the frequencies required for HD TV to work on Freeview – the auction means users of the service will be locked out of the technology.

The group is lobbying Ofcom, government and other stakeholders to ensure that enough spectrum is reserved to enable the BBC, ITV, Channel 4 and Five channels to broadcast in high definition.

The campaign wants parts of the spectrum kept apart from the frequency auction in order that Freeview viewers can get HD TV, which viewers of commercial subscription-based satellite and cable services already get.

"If the auction takes place as planned the millions of consumers who have purchased, or plan to purchase HD TVs may never be able enjoy high-definition TV on the Freeview platform," the campaigners argue.

The campaign emerges as Ofcom confirms one in four UK TV sets receive Freeview signals, and as the deadline for switching off analogue broadcasts in 2012 approaches.