Australian hard rockers AC/DC have announced Guns N' Roses frontman Axl Rose as their new singer, after news that Brian Johnson is unable to tour because he is suffering from hearing loss.

AC/DC confirmed the move hours before Rose took the stage with Guns N' Roses guitarist Slash at the Coachella festival in California as part of a long-awaited Guns N' Roses reunion.

The Coachella concert — which also featured a guest appearance from AC/DC guitarist and founding member Angus Young — saw Rose performing in a chair with his left leg in a cast.

AC/DC, who broke off a North American tour last month saying Johnson was at risk of permanent hearing loss, said Rose would make his debut with the band on a 12-show European leg starting on May 7 in Lisbon.

Rose — known for his soaring range and raw emotion — will then return to North America for the arena tour of the reformed Guns N' Roses, with the 10 postponed AC/DC dates in the United States to be rescheduled later.

"AC/DC band members would like to thank Brian Johnson for his contributions and dedication to the band throughout the years," the band said in a statement.

"We wish him all the best with his hearing issues and future ventures. As much as we want this tour to end as it started, we understand, respect and support Brian's decision to stop touring and save his hearing."

Johnson has been quiet in public and has reportedly voiced dismay at his swift exit.

US comedian and radio host Jim Breuer said he spoke to Johnson, who felt "kicked to the kerb" by his band-mates and did not believe his hearing problems were as serious as announced by the group.

Johnson, 68, known for his punishing vocal style, is not an original member of AC/DC.

The Englishman joined in 1980 after the death of original singer Bon Scott, and made his debut on the Back In Black album, which has sold more than 50 million copies.

Rose's entrance into AC/DC was first reported by radio station WNNX in Atlanta after the singer was spotted with the band in the city.

Brian Johnson (left) and Angus Young of AC/DC ( AFP )

The loss of Johnson is the latest major change for AC/DC. Malcolm Young, the rhythm guitarist and brother of co-founder Angus, retired before the Rock or Bust tour as he suffers dementia.

Drummer Phil Rudd was pushed out after he was arrested on charges of ordering a murder in New Zealand, where he lives.

Guns N' Roses became global sensations with 1987's Appetite For Destruction, which remains the best-selling debut album ever.

But friction was rarely far from the surface and the original line-up called it quits after closing a tour in 1993 in Buenos Aires.

A reunion had long been thought impossible, with Rose a few years ago calling Slash "a cancer." But the band had long enjoyed offers reported to be in the millions of dollars to reunite.

AFP/ABC