Green Day's Billie Joe Armstrong released from the hospital

From left: Tre Cool, Billie Joe Armstrong and Mike Dirnt of Green Day, photographed at Top of the Rock in New York City, May 16, 2009.
copyright Bob Gruen /
Singer Billie Joe Armstrong of the band "Green Day" performs in Caracas, Venezuela, on Oct. 8, 2010.

Updated: 12:00 p.m.

(CBS News) Green Day's Billie Joe Armstrong has been released from the hospital after being admitted over the weekend for treatment of an undisclosed illness, according to published reports.

Armstrong's hospitalization forced the band to cancel a concert in Italy, and it posted a YouTube apology.

The band was scheduled to play the I-Festival on Sept. 2 in Bologna, Italy, when the band's frontman succumbed to an unspecified illness, reports NBC News.

Armstrong's bandmates Tres Cool and Mike Dirnt posted a video message on YouTube apologizing to the fans.

"We're beyond devastated," said Tres Cool. "We're as sad as you guys are. Billie's extremely upset about it, and we'll see you very soon."

The band has three albums coming out, titled "Uno!," "Dos!" and "Tre!" The first album is due out Sept. 25.