NEW DELHI (Reuters) - Animals collapsed, people jumped on water tankers with buckets amid shortages and government employees changed their work hours as blistering summer heat kept its grip on north India on Thursday.

Although Thursday's readings were marginally lower in Delhi than the previous day when one area recorded an all-time high of 52.9 degree Celsius (127.22 Fahrenheit), the region still saw temperatures touching 47 C (116.6 F).

Delhi, which has a population of 20 million, recorded its first heat-related death on Wednesday, with a 40-year old labourer dying of heatstroke, local media reported. Authorities said they are investigating if the 52.9 C reading in the Mungeshpur neighbourhood on Wednesday was caused by a sensor error at the local weather station.

Television images showed people chasing water tankers or climbing on top of them in parts of the city to fill containers amidst an acute water shortage that the government blames on low levels in the Yamuna River - Delhi's primary source of water.

Along the river's banks, women in shanties endured stifling conditions in their homes as their cooking stoves aggravated the sweltering weather.

"The heat is worse this year. We work like this everyday so we get into the habit," said Seema, 19, who cooks for her family twice a day.

In the neighbouring state of Uttar Pradesh, a policeman used CPR to revive a monkey that he said had fainted and fallen from a tree because of the heat, pumping its chest for 45 minutes, local media reported, and Delhi also saw cases of heatstroke among birds.

As more people chose to order food and groceries by home delivery instead of venturing out in the heat, delivery personnel have been spending more time on their scooters and motorbikes, their employers said.

"Order frequency has been higher during the afternoon when people are avoiding stepping out," said Ateef Shaikh, a delivery fleet manager at a Swiggy delivery app store in Mumbai.

Zomato and its grocery delivery business, Blinkit, have taken additional measures to help delivery workers, including providing refreshments and comfortable clothing, their spokespersons said.

Blinkit is installing air coolers in the waiting areas of all its stores, the spokesperson added.

The extreme temperatures have also sparked more fires in several parts of the country, including in the northern state of Jammu and Kashmir, where authorities are using drones to monitor forest fires.

The country, which is nearing the end of multi-phase national elections, is not alone in experiencing unusually high temperatures. Billions across Asia are grappling with the heat and in neighbouring Pakistan the temperature crossed 52 C (125.6 F)this week.

Scientists say this trend has been worsened by human-driven climate change.

India, the world's third-biggest greenhouse gas emitter, has long held that, as a developing nation, it should not be forced to cut its energy-related emissions but has set a target of becoming a net-zero emitter by 2070.

(Additional reporting by Dhwani Pandya in Mumbai; Writing by Sakshi Dayal; Editing by YP Rajesh and Frances Kerry)

By Sakshi Dayal, Tanvi Mehta and Anushree Fadnavis