Nirvana were ''pretty lifeless'' at the end of their career.

The 'Heart Shaped Box' band's live shows were known for being past paced, ferocious and full of energy, but by Christmas 1993 - four months before frontman Kurt Cobain committed suicide - their former record label boss Bruce Pavitt could see signs of burnout.

He told NME magazine: ''The last time I saw Kurt he was performing in Seattle right around the Christmas holidays. It was a show for MTV and, frankly, I thought it lacked spark. I'd seen them from April 1988, I'd seen them from the very beginning. The band were pretty lifeless. It was kind of play-by-numbers and I could sense Kurt in particular seemed really burned out by the whole process.''

Journalist Keith Cameron also saw tensions within the band - completed by bass player Krist Novoselic and drummer Dave Grohl - which, alongside Kurt's heroin addiction, weren't helping.

He said: ''Things were not good internally within that band. It was just dysfunctional, and people were being horrible to other people ... clearly it's not going to go down well when you call someone's wife a, 'Grade A pain in the ass.' ''