At least one person has died and 200 others are in hospital due to an unidentified illness in India’s Andhra Pradesh state, according to reports.

The illness was detected on Saturday evening in Eluru, an ancient city famous for its hand-woven products. Since then, patients have experienced symptoms ranging from nausea and anxiety to loss of consciousness, doctors said.

A 45-year-old man who was in hospital with symptoms similar to epilepsy and nausea died on Sunday evening, the Press Trust of India news agency reported.

Officials are trying to determine the cause of the illness. So far, water samples from affected areas have not shown any signs of contamination and patients have tested negative for Covid-19.

State chief minister YS Jagan Mohan Reddy visited a government hospital and met patients who were ill. Opposition leader N Chandrababu Naidu demanded on Twitter an “impartial, full-fledged inquiry into the incident”.

Andhra Pradesh state is among those worst hit by Covid-19, with more than 800,000 detected cases. The health system in the state, like the rest of India, has been frayed by the virus.