The scientists are calling on the prime minister to press other world leaders at the G7 summit, starting in a week’s time, to halt the trade.
The UK government earlier this week put out a call for public views on banning imports and sales of real animal fur, with a view to issuing a ban.
The 67 experts from 16 countries who have signed the letter, including a former UK government chief scientific adviser, say fur farms provide ideal conditions for the creation and spread of new, deadly pathogens that can jump to humans.
Covid-19 has been found on 427 mink fur farms in 12 countries in Europe and North America, including 290 farms in Denmark, 23 in Greece, 69 in the Netherlands and 16 in the US, according to figures from Humane Society International (HSI).
The Danish government last year culled all the country’s 17 million mink to curb a Covid-19 mutation and because the animal was considered likely to host future mutations.
Together with China, Canada, the US and Russia, the country is one of the world’s biggest fur producers.
The letter to Mr Johnson, environment secretary George Eustice and health secretary Matt Hancock says: “Fur farms have the potential to act as reservoirs of Sars-CoV-2.
“The intensive breeding conditions typical on fur farms – animals unnaturally crowded together, poor hygiene, stress, injuries and low genetic diversity – are ideal for the creation and spread of novel pathogens.
“The trade creates potential for the many tens of millions of animals on fur farms to act as immediate, intermediate or amplifier hosts for viral pathogens.
“To risk jeopardising our ability to control and end this or future global coronavirus pandemics, for the sake of fur fashion production, would seem imprudent.”
It was signed by vets, virologists and epidemiologists, including Alastair MacMillan, a former government chief scientific adviser and chief vet, and Alick Simmons, a former government deputy chief vet. Scientists from the US, Italy, Germany, Canada and France also signed.
The letter points out that “a significant number” of fur farm workers have caught Covid from mink, citing test data.
And infection in mink can lead to mutations of the virus, which potentially risks undermining vaccines, it adds.
Each year the trade worldwide kills at least 100 million animals, mostly mink and raccoon dogs, which are susceptible to catching and spreading coronaviruses.
Claire Bass, executive director of HSI/UK said: “We can no longer ignore that fur farms make for a perfect petri dish for pandemics.
“As the first country in the world to ban fur farming two decades ago, the UK as G7 host is in a unique position to urge world leaders to take decisive action.”
The Netherlands has been phasing out mink farming since the outbreak. In France, a ban is going through parliament.
California became the first US state to ban fur sales in 2019, following local bans in Los Angeles, San Francisco, Berkeley and West Hollywood.