It is D-day for digital radio. Britain's radio groups, media regulator Ofcom and the Department for Culture, Media and Sport will meet at an emergency summit tomorrow to discuss whether to combine Britain’s two nationwide transmission platforms - Digital One (D1),the transmission platform that Heart owner Global Radio inherited on its acquisition of GCap Media, and Digital Two (D2) and Digital Two, the second platform of channels originally awarded to Channel 4 but now being mothballed.

It is understood that Ofcom, the government and radio groups are frustrated that no decision has been reached, as it has stalled the launch of new stations, such as Channel 4’s E4 Radio.

Many people have been critical of Channel 4’s radio spend, particularly as it is in the middle of a funding crisis and has yet to launch a station.

Ofcom has been planning to redraw its licensing rules for digital radio to encourage Global Radio and Channel 4 to combine their efforts. Sources said last night that one possibility that could be raised include putting E4 Radio on to D1 to enable a quicker launch. Other stations from Channel 4 could then be launched on Digital Two at a later date.

Further suggestions could see Channel 4 and its minority partners in the multiplex, which include Bauer Radio and UTV, taking a 65 per cent stake in Digital One (D1).Global and Arqiva, its network partner, would then take a stake in Digital Two (D2)

A further possibility is that D2 will eventually become a mix of national and regional stations, allowing Global to launch a nationwide Heart station.