Janet Jackson is in the midst of a North American concert tour but has cancelled a Montreal show after feeling “suddenly ill” during sound check on Monday.

The 42-year-old singer was performing a sound check Monday in Montreal, Canada and suddenly felt ill, a representative has explained. A statement released by W&W Public Relations gave few details regarding the nature of Jackson’s illness and the continuity of her tour.

Jackson required immediate medical attention and was taken to an unspecified hospital just before the show was about to start. The statement further said she hopes to reschedule the concert but no possible date has been offered yet.

She is being monitored at the respective hospital. No details regarding her condition were offered and the public is left to speculate whether the great effort of preparing the tour has taken its toll on the singer’s health or whether she had been previously suffering from some condition.

Fans learned they would not see the iconic 1980s singer Monday night just minutes before LL Cool J was about to open the show, reports MTV.com.

Janet Jackson released her tenth studio album “Discipline” in February, with new record label Island Def Jam, which she signed with little over a year ago. The album has received generally positive reviews from music critics, selling some 415,000 in the U.S. as of September.

It became her sixth studio effort to debut at No. 1 on the Billboard 200, a spectacular event which guaranteed an honorary place for Jackson among the few select female artists with most No. 1 albums. Barbra Streisand remains the reigning queen, with eight No. 1 albums, followed by Madonna with seven, while Mariah Carey and Jackson tie for the second most No. 1 albums, at six.

The Rock Witchu Tour, Jackson’s fifth concert tour and the first in nearly seven years, kicked off on September 10, in Vancouver, Canada. In May, Jackson told the Associated Press that she was already busy rehearsing for the upcoming tour, which in fact was long overdue.

Jackson had wanted to do a tour in support of 2006’s “20 Y. O.,” which she ultimately abandoned at the request of her then-record label, Virgin Records, she said.
Rock Witchu has not been without complications so far. Last Friday, Jackson cancelled another concert, this time in Detroit, due to “production constraints.”

She is scheduled to entertain fans in Boston, Philadelphia, Greensboro and Atlanta in the following days.

The singer last toured in 2001, in support of her “All For You” album and she did so most successfully, as that tour became one of the year’s highest grossing.