Legendary singer Lata Mangeshkar was admitted to Breach Candy Hospital's Intensive Care Unit in the early hours of Monday after she complained of breathing problems, hospital sources said.
The singer, who turned 90 on September 28, is in a critical condition, they said.
"She was brought to hospital at about 2 am. She is critical and in the ICU," a hospital insider told PTI.
Mangeshkar's younger sister Usha said the singer had a viral infection and should be discharged by Tuesday.
"Lata didi is still in hospital. She is under observation. She is doing absolutely well and is stable. She will be discharged by tomorrow.
"We thought it's better to treat her at a hospital because of the viral infection so she is there for today," Usha Mangeshkar told PTI amid reports that the musical icon had already been discharged and was recuperating at home.
In a career spanning over seven decades, the Indore-born Mangeshkar has lent her voice to thousands of songs in over 1,000 Hindi films as well as in various regional and foreign languages.
The indefatigable Mangeshkar recorded her last song this year. "Saugandh mujhe is mitti ki" was released on March 30 as a tribute to the Indian Army.
Her last full album in 2004 was "Veer-Zaara" when she was 75.
She started her journey as a playback singer in 1942 with Vasant Joglekar's Marathi movie "Kiti Hasaal". Her first song to release was "Natali chaitraachi navalaai" from "Pahili Mangalaa-gaur". She also acted in the movie.
Mangeshkar was awarded the Bharat Ratna, the highest civilian honour in the country, in 2001.
She was given the Dadasaheb Phalke Award in 1989.