Thousands of people have signed a petition against elephant riding after an animal ferrying tourists to the famous Angkor Wat temple complex in Cambodia died.
The elderly elephant had been working in a 40C (104 F) heatwave.
The tour operator has pledged to reduce elephants' working hours until temperatures drop.
But the petition asks authorities in the Angkor region to ban elephant-riding outright.
Cruelty is often "hidden from view", the petition says, causing a "lifetime of misery" for the animals, and the elephant's death should be "a wake-up call".
Animal rights groups have long complained of cruel training practices used on captive elephants. The charity World Animal Protection named elephant rides as the top most cruel holiday activity in a list it created for campaign purposes.
Some tour companies including STA, Intrepid and Costco have now stopped promoting the activity.
Oan Kiri, a manager at Angkor Elephant Company, told AFP news agency the female elephant had collapsed after working for 45 minutes and walking 2.1km (1.2 miles).
"Veterinarians concluded that the elephant's death was caused by the hot temperatures which caused stress, shock, high blood pressure and a heart attack," he said.
It had been aged between 40 and 45 years, which is towards the end of an Asian elephant's lifespan.
Asian elephants are classified as an endangered species by the International Union for Conservation of Nature. There are about 70 domesticated elephants in Cambodia.