Popular Japanese singer-songwriter Hikaru Utada has been hospitalized and will undergo a thorough medical examination possibly Tuesday, her record company Toshiba EMI Ltd. said Sunday.

Utada, 19, had been working under medical supervision after recovering from an operation to remove a benign tumor from her ovary, but her condition deteriorated a couple of days ago, the record company said.

She first fell ill at the beginning of April. While the operation was successful, Utada suffered side effects from her medication, it said.

Utada will cancel all her bookings until May 21, her music office said.

The star's 1999 debut album "First Love" was a hit in Japan and sold more than 9 million copies. Her albums and singles, including her latest work "Hikari," have consistently topped music charts.

In February, Utada also signed a contract with a major U.S. record label, and she plans to release an album in English.