NEW YORK (AP) — Vocal problems have forced Jordin Sparks to temporarily withdraw from Alicia Keys' tour and cancel all performances for the rest of the month, a representative for the "American Idol" champ said Monday.

"All of her April activities have been postponed or canceled so she can take care of her voice properly," a 19/Jive Records spokeswoman told The Associated Press.

The 18-year-old singer, whose hits include "Tattoo" and "No Air," was scheduled to be the opening act on Keys' tour, which kicked off over the weekend in Hampton, Va. In addition to missing the tour's first month, Sparks was forced to cancel a planned performance at the Earth Day Network & Green Apple Festival concert in Washington, D.C.

But Sparks, who is under a doctor's care, is expected to rejoin Keys' tour in May or perhaps sooner if she progresses, the label said.

"Jordin Sparks is on vocal rest and is expected to make a full and complete recovery," according to a statement from 19/Jive Records. "Sparks has been going nonstop over the past two years and now she's going through the normal course of learning how to manage and care for her voice."

Sparks was the youngest winner of "American Idol" when she won the talent competition last year. She released her self-titled debut album late last year.