Nearly a third of the UK's 60 million TVs still aren't connected to digital services from the likes of Sky, Virgin or Freeview, according to a new Ofcom study.

Ofcom's Digital Progress Report warned that 22 percent of TVs aren't connected to satellite, cable or digital terrestrial services, but said the total number of sets linked to digital services increased by seven million in the first three months of 2008.

The communications regulator wants to boost awareness of the need to switch to digital, as the analogue TV signal is due to be switched off by 2012.

Sky remains the UK's most popular digital TV supplier. Ofcom's report said the satellite broadcaster has 8.3 million subscribers. Virgin has 3.5 million subscriptions.

Meanwhile, digital terrestrial services continue to perform strongly, with 30 million Freeview set-top boxes, PVRs and integrated digital TVs sold since 2002.