Bob Geldof found it ''exhausting and embarrassing'' calling stars for Band Aid 30.

The 63-year-old singer has been the guiding force behind the charity single, as he was with the original 'Do They Know It's Christmas?' in 1984, and he's admitted it wasn't easy to get so many big names to record the track.

He reflected: ''It's a song, it's a track, but it's an event and the next stage is to turn it into a phenomenon like it was in the '80s. And the only way to do that is to get people to buy the thing.

''Spare me this free economy. Spare me Spotify and YouTube. There's a donate button on YouTube. Hit the donate button. It's a badge of honour to have this on your phone or on your iPod, or whatever the hell you're using. And don't buy one. Buy several. Give them to your mates.''

U2 frontman Bono - who has appeared on three of the four versions of 'Do They Know It's Christmas?' - is among the stars set to appear on the eagerly-awaited track and he said: ''I just wish we didn't have to do this. There will come a time when we won't. And it will be great not to see the same old faces.

''What's great about today is it's like Star Trek: The Next Generation.''

One Direction, Ellie Goulding and Coldplay's Chris Martin are all set to feature on the track, which will raise money for the Ebola crisis in Africa.