Scorching temperatures have hit many Asian countries this week, prompting the school closures in the Philippines and Bangladesh due to extreme heat forecasts.

Roads minister Nitin Gadkari fainted during his speech on Wednesday at a small town in the western state of Maharashtra, where he was campaigning for the re-election of Prime Minister Narendra Modi's government.

Footage of the incident showed the minister falling unconscious and being carried off the stage by handlers.

"I felt uncomfortable due to the heat during the rally," Gadkari wrote on social media platform X later that day.

"But now I am completely healthy," he said, adding that he was going ahead with his election campaigning.

The Indian Meteorological Department said on Thursday that severe heatwave conditions were likely to continue in at least nine eastern and southern states over the next five days.

"Heatwave to severe heatwave conditions (are) very likely to prevail," the statement said, with temperatures already reaching 44 degrees Celsius (111.2 Fahrenheit) in some locations.

Large outdoor campaign rallies are being staged across India with the country in the middle of a marathon election staggered across six weeks.

Tens of millions of people are due to vote in the poll's second phase on Friday.

India's election commission said this week that it was reviewing the impact of heatwaves and humidity before each round of voting with a view to "mitigatory measures" that would still allow citizens to cast their ballots.

Years of scientific research has found climate change is causing heatwaves to become longer, more frequent and more intense.