Delhi's water minister Atishi has been admitted to hospital, five days after she began a hunger strike to highlight the city's water crisis.
The Indian capital has been facing severe water shortages as a prolonged heatwave has pushed up consumption.
Ms Atishi was taken to hospital on Tuesday morning after her sugar levels dropped to 36 - way below the normal range of 70-100mg/dL.
The Aam Aadmi Party (AAP) leader, who goes by only one name, has accused neighbouring Haryana state of restricting water supply to the city.
But the Bharatiya Janata Party (BJP), which is in power in Haryana, has denied the charge and blamed the AAP government for the water crisis.
"She has not eaten anything for the last five days," AAP leader Saurabh Bharadwaj wrote on X (formerly Twitter), adding that she was being treated in the ICU.
Delhi is experiencing one of its hottest summers this year, with temperatures crossing 40C for weeks.
This has led to a spike in the demand for electricity and water, putting a strain on the city's resources.
With the water supply almost running out, people have had to depend on water supplied by tankers.
Ms Atishi has blamed the Haryana government for holding up a large share of water from river Yamuna, which runs through the capital.
Delhi and other northern states, including Haryana, depend on the river for their water needs.
In 1996, India's top court ordered Haryana to provide a portion of its water to Delhi throughout the year because of the city's growing demands for drinking water.
But last week, Ms Atishi requested the Haryana government to release additional water to the city on "humanitarian grounds".
The minister also alleged that for the past three weeks, Haryana had reduced water supply to the capital by 100 million gallons per day, depriving 2.8 million people of their needs.
The Haryana government, in turn, accused Delhi of mismanagement and said that authorities were responsible for the city's water crisis.
