Liza Minnelli collapses on stage

(CNN) -- Liza Minnelli collapsed during a Christmas performance in Sweden and returned to the United States on Thursday for treatment, her spokeswoman and a concert organizer said.

A statement on the performer's Web site said Thursday, "Liza is fine."

Minnelli, 61, was performing in Gothenburg on Wednesday night in a concert called "A Classic Christmas Night," said Zlatko Nedanovski, who works for the company organizing the show. He said Minnelli felt unwell and nauseous before the concert but decided to perform anyway.

"She performed four songs, which was about half her set," Nedanovski said. "She felt unwell, walked towards the stairs behind the stage, took her first step off the stage, became unconscious, and fell into the arms of someone walking with her."

He said the audience saw Minnelli collapse.

"She remained unconscious for about five seconds. She seemed very dizzy afterwards," he said.

Minnelli's manager rushed her back to her hotel room, said Minnelli spokeswoman Liz Rosenberg.

"A doctor upon examining her and in consultation with her NY physician determined that it would be necessary for the Oscar-winning actress and singer to immediately return to New York City to receive further medical examination," Rosenberg said in a statement.

Nedanovski said the concert was the last of four scheduled in Sweden -- two in Stockholm over the weekend and two in Gothenburg this week.

He said he suspected Minnelli may have been upset that her European agent, Mustafa Metin, was jailed after allegedly assaulting a photographer Dec. 8, and upset at poor reviews for her Tuesday show.

"She was a bit shaky and upset on the 12th because of the incident involving Metin and she didn't get good reviews for her concert on the 11th," Nedanovski said.

A statement on Minnelli's Web site said her planned concerts in Copenhagen, Denmark on Friday and Saturday were canceled, but her Jan. 12 concert in Providence, R.I. was still on.

"All is fine, Liza is fine, and the tour is continuing, otherwise, as scheduled," the statement reads.

Minnelli won the 1973 Academy Award for best actress for her role in Cabaret. She won an Emmy the same year for her TV variety show, "Liza with a 'Z.'"

She has won two Tony Awards, in 1965 and 1978.

Minnelli is the daughter of Judy Garland and movie director Vincente Minnelli. E-mail to a friend

CNN's Jonathan Wald contributed to this report.