AC/DC's Malcolm Young is ''too sick'' to perform live with the band anymore.

The 61-year-old guitarist, who founded the Australian rock group with his brother Angus in the 1970s, is said to be seriously ill, sparking rumours the band could split after 41 years.

In an interview with Australia's ABC radio, Choirboys frontman Mark Gable, who is close friends with Malcolm and Angus, said: ''From what I understand, and it's even been confirmed in part by his son Ross, that it would appear Malcolm is unable to perform anymore

''It's not just that he is unwell, it's that it is quite serious. It will constitute that he definitely won't be able to perform live.

''He will probably not be able to record.''

He claims the band could still continue with plans for their 40th anniversary world tour and go on to record their first album since 2008's 'Black Ice' without Malcolm, after his nephew Stevie took his place during a past tour.

Mark explained: ''There was speculation that they had this even tacit agreement that if no member currently was able to perform, DC would cease.

''However, Alex Young's son Stevie replaced Malcolm Young a few years back for a tour, and nobody knew the difference.''

Mark has been close friends with AC/DC, also made up of singer Brian Johnson, bassist Cliff Williams and drummer Phil Rudd, for a number of years after the Choirboys recording their first album in the same studio where the 'Whole Lotta Rosie' hitmakers worked on their first five records.

Regarding a world tour, Brian previously said: ''It's been 40 years of the band's existence, so I think we're gonna try to do 40 gigs, 40 shows, to thank the fans for their undying loyalty.''

The rock legends were also due to head back into the studio next month.