Whitney Houston's long-awaited comeback has suffered a setback - thanks to her years of drug abuse.

The recording of the troubled singer's new album has had to be postponed after she was unable to hit the high-notes for some of her most famous songs.

"She was smoking a lot and taking a lot of drugs. Her voice was almost unrecognisable.

"Thousands have been shelled out to train her back up to the original,” a source tells The Mirror.

But after some emergency singing lessons -  at the behest of top industry mogul Clive Davis – the insider reports that Whitney is now sounding “terrific” and her new as yet untitled record is on course for a November 10 release.