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.