(CNN) -- Amy Winehouse has canceled the remainder of her 12-city European concert tour, the singer's representative said Tuesday.
"Everyone involved wishes to do everything they can to help her return to her best and she will be given as long as it takes for this to happen," representative Chris Goodman said in a statement.
Audience members in Belgrade, Serbia, booed Winehouse off the stage Saturday night just a few songs into the first concert of the tour.
Videos recorded by audience members showed Winehouse apparently having difficulty singing some of the lines of her songs. Audience members and her back-up singers filled in the gaps at times.
Winehouse on Sunday canceled appearances in Istanbul and Athens. The decision to cancel the remainder of the tour was announced Tuesday.
Winehouse recently left a British rehab program that a representative said was intended to prepare her for the European concerts.
On Sunday, Winehouse representative Tracey Miller did not directly confirm that the "Rehab" singer, who has a history of battling drugs and alcohol, had begun drinking or using drugs again.
"Despite feeling sure that she wanted to fulfill these commitments, she has agreed with management that she cannot perform to the best of her ability and will return home," Miller said over the weekend.
CNN's Denise Quan and Per Nyberg contributed to this report.