The "sunions", which have been available in the US since 2018, are said to be a sweet variety of the vegetable that "doesn't reduce cooks to tears".

Grown in Spain, they will retail at £1.50 for a three-pack when they go on sale online and in selected stores from Tuesday next week.

That works out at 50p an onion, compared with 14p for a typical essential 150g onion bought loose from the supermarket.

The products were first developed by agricultural giant Bayer - then taken over by chemicals firm BASF when it acquired some of Bayer's seeds and crop business.

They were not created through genetic modification, instead coming about after decades of cross-breeding of less pungent strains of onion.

A website promoting the products says: "Volatile compounds in onions are responsible for tearing and pungent flavour and the amounts of those compounds in other onions remain the same or increase over time.

"In Sunions, these compounds do the exact opposite and decrease to create a tearless, sweet and mild onion."

However, the products were described in a review published by the Washington Post - which confirmed they did not cause tears - as "flavourless".

Waitrose said the tearless onions were "perfect for those with sensitive eyes as well as cooking in the kitchen with children".

On the question of whether they could be used to make a spicy dish, a Waitrose spokesperson said: "They're a sweet onion so still work in a curry but also can be served raw."