Amy Winehouse is to cancel part of her European tour after the singer was booed for appearing to be too drunk to perform at a concert in Serbia's capital Belgrade.
She is pulling out of shows in Istanbul, Turkey, on Monday, and Athens, Greece, on Wednesday.
A spokesman said Ms Winehouse would like to apologise to fans, but "feels that this is the right thing to do".
The singer has struggled with addiction for some time.
Her spokesman added that Ms Winehouse will return home after agreeing with management that "she cannot perform to the best of her ability".
Her tour, which was originally scheduled to include 12 performances, is now due to resume in Bilbao, Spain, on 8 July.
The concert in Belgrade was the first of the tour, and for almost 90 minutes, Amy Winehouse mumbled her way through parts of songs, said the BBC's Mark Lowen.
He added: "She sang a few strained notes, before stumbling across the stage and at one point throwing her microphone to the floor.
"At times she left the stage altogether - her band attempting to fill in.
"She was frequently booed by the crowd. Many had paid up to €45 (£40) to see her in a country in which wages are some of the lowest in Europe, and their anger was clear."
The Grammy-award winning singer had been under strict instructions not to drink after recently finishing a course of alcohol rehabilitation in London.
Hotel staff on her European tour are said to be under orders to remove alcohol from her room.