Rocker Billie Joe Armstrong is entering rehab.

The Green Day singer is set to undergo treatment for substance abuse, a spokesperson for the group has confirmed. The band has also postponed several upcoming promotional appearances.

"Green Day wants to apologize to those they offended at the iHeartRadio Festival in Las Vegas. The band regretfully must postpone some of their upcoming promotional appearances," the Grammy award-winning singer's representative told TMZ.

The group's front man had a very public meltdown on stage in Las Vegas over the weekend, where the group was performing at the star-studded iHeartRadio Music Festival. The 40-year-old singer was videotaped screaming profanities and slamming Justin Bieber during the band's performance at the annual three-day festival before violently smashing his guitar on-stage, complaining their performance had been cut short.

Billy was hospitalized in Italy earlier this month for an undisclosed ailment, but recovered in time for his band to perform at the MTV Video Music Awards on September 6. Green Day will release their new album Uno on Tuesday - the first in a trilogy of records - and is due to kick off a new US tour on November 26 in Seattle.