Army rescue teams have joined the relief effort, as people waded through waist-high waters that have partly submerged vehicles and roads, visuals from Reuters television showed.

"There is no electricity for the last two days," said Prabhu Ram Soni, who lives in the coastal city of Jamnagar. "I have an eight-month-old daughter and an asthma patient, my mother, who is on oxygen support."

Since Sunday, 28 people have died from drowning and rain-related causes, while more than 18,000 have been evacuated from cities near the coasts, disaster management authorities said.

Heavy rains continued in Jamnagar, home to the world’s largest oil refinery complex, owned by Reliance, the district collector, B K Pandya, told Reuters.

At nearby Vadinar, Nayara Energy, backed by Russian groups including its largest oil producer, Rosneft, runs another refinery.

"They are operational," Pandya said, when asked if rain had affected work in the refineries, adding that authorities were focusing on rescue efforts in the district.

India’s weather office has warned of extremely heavy rainfall forecast on Thursday in Gujarat s districts of Bharuch, Kutch and Saurashtra, with Friday expected to bring heavy rain, thunderstorms and lightning.

The rains have been caused by a deep atmospheric depression off the coast of Gujarat, which has also affected the southern coast of neighbouring Pakistan, with its largest city of Karachi lashed by heavy rain.

Officials in Pakistan’s southern province of Sindh warned against torrential rain, rough seas and flooding expected on Thursday, as the weather system moves westwards from India.

After recent heavy rains lashed the port city of Karachi, authorities have warned of flash floods in two districts of Sindh still recovering from 2022 floods that inundated large swathes of the country.