Janet Jackson was released from a Montreal hospital just two hours after she arrived, a spokeswoman for the facility said Tuesday, but it was still not clear why she was admitted.

The 42-year-old singer became "suddenly ill" and was taken to Royal Victoria Hospital on Monday night shortly before her scheduled concert in Montreal, which was canceled, according to a statement released by W&W Public Relations.

Jackson was at Royal Victoria but was released two hours later, said Rebecca Burns, representative for McGill University Health Centre, which runs the hospital. Representaives for Jackson would not elaborate on her condition Tuesday, simply saying that she was ill and was "recuperating."

Meanwhile, Jackson's shows in Boston and Philadelphia on Wednesday and Thursday were postponed and she was due to resume her tour in Greensboro, N.C. on Saturday. There was no information on when those shows would be rescheduled.

Jackson, who is on her first North American tour in seven years, dropped out of her scheduled "Saturday Night Live" performance in March because she had the flu, and her publicist said at the time that she went to the hospital for treatment but was not admitted.