Black Sabbath bassist Geezer Butler has revealed that he penned a song about bandmate Tony Iommi's cancer following his diagnosis.

Iommi has been battling lymphoma throughout the group's reunion and when Butler, learned of his health crisis he felt inspired to get his thoughts and feelings out in lyrics for a track he tentatively titled 'Hanging By A Thread'. He told Revolver magazine: "It was very much about dying, about giving your last breath and passing your spirit on. But the track didn't make it on (the band's comeback album) '13'. We never came up with the finished thing."

Butler admitted that he feared the worst for his bandmate - because former frontman Ronnie James Dio also lost his battle with cancer in 2010. He added: "We didn't know if he (Iommi) was going to recover from it, especially after seeing Ronnie go so fast. Ronnie went right in six months from being diagnosed to dying."

Meanwhile, the rock veterans recently took three gongs home at the Classic Rock Roll of Honour awards. The band, fronted by Ozzy Osbourne, 64, won the Album of the Year, Event of the Year and were given the Living Legend prize.

The reunited band reached Number One in the UK Official Album Chart this year with '13', their first album since 1995.