Street traders in India — as well as southeast Asia — are risking starting dangerous diseases like coronavirus by keeping animals for consumption in squalid conditions, an investigation has found.

Goats, lambs and chickens are sold from cramped cages in scenes mirroring those in live animal markets in Wuhan, China, where Covid-19 originated, according to witnesses.

In exclusive footage captured in China, Vietnam and India, animals such as deer, crocodiles, raccoons, cats and dogs can be seen living in filthy conditions, where the investigators said dehydration, starvation and disease were rife.

The videos were taken at “wet” markets — where animals from cats to crocodiles are slaughtered on demand for customers, and people are in constant close contact with animal body parts and bodily fluids, including blood.

Scientists strongly believe it was at such a market where Sars started in 2003-4, and also in Wuhan where Covid-19 virus, which has killed more than 45,000 people worldwide, began.

Researchers for Animal Equality said that since 2014 they have seen chickens, lambs and goats being sold for slaughter in India both on the street and in shops, “creating the perfect breeding ground” for zoonotic diseases — those passed from animals to humans.

In February, after the outbreak of coronavirus, the Chinese government temporarily banned the sale of wild animals for consumption, but street traders said they planned to resume as soon as the ban was lifted.

On Wednesday, the city of Shenzhen became the first in the country to permanently to ban the consumption and production of dog, cat and wildlife meat in stores, markets and restaurants.

Investigations by wildlife trade monitoring network Traffic have previously found wet markets in India illegally selling turtles and occasionally parts of other wild species.

Killing chickens on demand at the roadside is common in the country, and animal-welfare campaigners say all types of open-air slaughter pose health risks to humans.

Abigail Penny, executive director of Animal Equality UK, said: “Wet markets are filthy, nightmarish places. The overwhelming fear that these poor animals suffer is unimaginable. But also, time and again wet markets have been the source of dangerous viruses — they are a major threat to human health, there’s no doubt about it.

“It’s not enough to close them temporarily, wet markets need to go once and for all.”

Amruta Ubale, of Animal Equality India, said: “There are some wet markets that are still open in India, while the rest are closed. Many individual meat shops (not situated in markets) are still open and are slaughtering animals like chickens in the shops as they usually do.”

Previous research has found pangolins butchered for their scales, which are then sold on the black market for traditional Asian medicine in India. Pangolins are believed to have been a key carrier of the coronavirus before it passed to humans.

And similar work also uncovered an international trade in monitor lizards for their body parts after the animals are poached in India.

Professor Andrew Cunningham, of the Zoological Society of London, said: “The animals have been transported over large distances and are crammed together into cages. They are stressed and immunosuppressed and excreting whatever pathogens they have in them.

“With people in large numbers in the market and in intimate contact with the body fluids of these animals, you have an ideal mixing bowl for [disease] emergence.”

Dr Ian Lipkin, an infectious disease expert at Columbia University’s Mailman School of Public Health, said: “If you take wild animals and you put them into a market with domestic animals or other animals, where there’s an opportunity for a virus to jump species, you are creating … a superhighway for viruses to go from the wild into people. We can’t tolerate this any more. I want the wild animal markets closed.”