Disaster response teams have been deployed to rescue dozens of people in the state, where residents are bracing for more heavy monsoon rainfall.

"Deaths in rain-related incidents in Gujarat rose to 27 on Wednesday, with nine more deaths reported during the day," the state government said in a statement.

The figure raises an earlier toll of 18, with most of the latest deaths caused by drowning, the government said.

The worst-hit areas included Palitana and Jesar towns, which on Tuesday registered 867 millimetres (34 inches) of rain over the past 24 hours.

State relief commissioner Alok Kumar Pandey said Tuesday the first 18 deaths recorded were the result of storms, lightning strikes, and structural collapses due to rough weather.

"The state is fully geared to handle the situation, and inter-departmental coordination is being intensified to ensure swift relief and rescue operations," Pandey said.

Those rescued included 18 farm labourers who were trapped in mango orchards in the Gadhada area, and 22 people in the Surendranagar district where waters from an overflowing river gushed into their homes.

India's annual monsoon season from June to September offers respite from the intense summer heat and is crucial for replenishing water supplies.

But scores of people die each year during the rainy season due to flash floods and landslides across India, a country of 1.4 billion people.