Many power plants in India, including those owned by Adani Power and Tata Power use imported coal, but were not operating at full capacity, adding to challenges for the country in meeting its power demand amid an ongoing heat wave.

Various places in India have been reeling under severe heat over the last few weeks, with maximum temperatures hitting 42-44 degrees Celsius over parts of Central, Northwest, East, and North India on Saturday.

India initially said in February these plants were to operate at full capacity till June 15, as the government looked to maximise output ahead of an expected record surge in power usage during the summer.

"It has now been decided to extend the time period for... directive to imported coal-based generators, up to September 30," the order issued by the Ministry of Power on Monday states.

The order has been sent to JSW Ratnagiri Ltd., Essar Power Gujarat Ltd and 13 other factories totalling a capacity of 17 gigawatts.

The India Meteorological Department, in a press release on Sunday, said that heat wave conditions are "very likely" to continue in isolated pockets of several states over the next five days, including the national capital New Delhi.

(Reporting by Sarita Chaganti Singh, writing by Sakshi Dayal; Editing by Kim Coghill and Nivedita Bhattacharjee)