(Cover) - EN Showbiz - Kings of Leon band members have reportedly urged lead singer Caleb Followil to enter rehab.

The American rock band cancelled their US tour yesterday because they said Caleb was "suffering from vocal issues and exhaustion".

But Us Weekly are reporting the singer may have other problems which contributed to the concert dates being called off.

"They are trying to get Caleb to go to rehab. It is mostly for alcohol," the source told the publication.

"[That's why] they ended up cancelling the whole tour... he drinks like a fish."

During Friday's concert in Dallas, Caleb left the stage telling fans that he was "gonna vomit" and going to "drink a beer".

"It's true," a second source said. "Caleb's drinking is out of control and they are trying to get him into rehab. It's a dark demon he has been fighting for a while."

"There are internal sicknesses & problems that have needed to be addressed," Caleb's bandmate and brother Jared wrote on Twitter over the weekend. "I know you guys aren't stupid. I can't lie. There are problems in our band bigger than not drinking enough Gatorade."

Jared added that he was "utterly depressed" about the cancellation of the US leg of the tour but said that, "family has to come first".

A representative told the site that the reason for cancelling the tour is because Caleb is under doctor's orders for vocal rest.

The band has said they will resume the shows in Canada in September. (C) Cover Media