Two days after his on-stage outburst at the iHeartRadio festival made headlines, Green Day frontman Billie Joe Armstrong has announced he will undergo treatment for substance abuse. 
 
 The band broke the news Sunday evening on their Facebook page, posting a message that read: 
 
 "Billie Joe is seeking treatment for substance abuse. We would like everyone to know that our set was not cut short by Clear Channel and to apologize to those we offended at the iHeartRadio Festival in Las Vegas. We regretfully must postpone some of our upcoming promotional appearances." 
 
 At press time, it's not clear just what appearances will be scrapped in support of the band's ¡Uno! album (out Tuesday), or if Armstrong's treatment will effect Green Day's just-announced tour, which is set to kick off in November. A rep for the band could not be reached for comment by MTV News. 
 
 Armstrong launched into a rant during Green Day's Friday-night performance at iHeartRadio after being told that the band needed to wrap up their set, shouting "I'm not f---ing Justin Bieber, you motherf-----s. You've got to be f---ing joking ... I got one minute left." Green Day then smashed their instruments before departing the stage. 
 
 And earlier this month, Green Day were also forced to cancel a concert in Italy after Armstrong was hospitalized. His bandmates would subsequently tell MTV News that he had "severe dehydration," though he recovered in time to perform at the 2012 MTV Video Music Awards. 
 
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 Green Day Frontman Enters Rehab After On-Stage Meltdown 
 
 Breaking News 
 
 's front manis entering rehab for substance abuse ... a rep for the band tells TMZ.The news comes just two days after Armstrong went ballistic in Vegas during a performance at the iHeart Radio Music Festival. He was videotaped screaming obscenities, slamming Justin Bieber and violently smashing his guitar on-stage.The band's rep tells TMZ, "Green day wants to apologize to those they offended at the iHeartRadio Festival in Las Vegas." 
 
 The rep adds, "The band regretfully must postpone some of their upcoming promotional appearances.“ 

 The lead singer of the US rock band Green Day has admitted he is seeking help for substance abuse. 
 
 A statement on the band's website revealed that Billie Joe Armstrong was receiving treatment. 
 
 It comes hours after he stormed off stage at the iHeartRadio festival in Las Vegas ending the band's set. 
 
 A sign had appeared saying they had one minute left to perform but Green Day's website confirmed that the set had not been cut short. 
 
 Band statement 
 
 The organisers said that Green Day's set was not curtailed and afterwards Billie Joe was "pumped and laughing backstage". 
 
 Green Day's website apologised to fans who were offended. 
 
 It said: "We would like everyone to know that our set was not cut short. 
 
 We regretfully must postpone some of our upcoming promotional appearances Statement from Green Day 
 
 "We regretfully must postpone some of our upcoming promotional appearances." 
 
 In a number of online videos the front man is seen stopping the band's set mid-song, swearing repeatedly and smashing his guitar. 
 
 The news that he is "seeking treatment for substance abuse" comes after he was admitted to hospital in Italy earlier this month. 
 
 It was said then that the singer was suffering with "an illness" - they were back on stage a couple of days later at the MTV VMAs in Los Angeles. 
 
 Currently in the middle of a world tour promoting their new album Uno! the group played at London's Shepherds Bush Empire and Reading festival in August. 
 
 The trio, who have a number of high-profile TV appearances and gigs booked this week to promote their new album, have yet to confirm which ones are affected.
– Green Day frontman Billie Joe Armstrong is checking himself into rehab after a rant mentioning Justin Bieber last week in Vegas. Armstrong ended the band's performance at the iHeart Radio Festival after an obscenity-laced tirade, smashing his guitar, then storming off stage. "I'm not effing Justin Bieber," Armstrong screamed after he thought he had been told to wrap up the set, according to MTV. "Green Day wants to apologize to those they offended," reads a statement on the band's website. "We regretfully must postpone some of our upcoming promotional appearances." What substances Armstrong has been abusing were not revealed.