The variety has been developed by a five-grower consortium involving The Moulton Bulb Company, Bedfordshire Growers, G's Marketing, F B Parrish & Son and Rustler Produce.

Funding in the three-year development stage was attracted through the government's LINK project and the variety itself was developed by scientists at Horticulture Research International.

This year, planting has been increased so that 300 tonnes are available between June and October.

Co-ordinator, David O'Connor, director of the Allium & Brassica Centre at Kirton, Lincs told the launch party's growers, marketing organisations and supermarket buyers he believes there is vast potential for the new product in the salad and food-service sectors. It also has a valuable role to perform in replacing imports from Spain.

First scientific taste-testing trials by Liverpool University have produced some extremely encouraging results. Using the concentration of pyrovate in onions to define strength, Supasweet proved to have the lowest reading compared to brown onions and even imported white varieties. It scored a just-under-five on a scale of one to 10.

Sold in trials last year, Supasweet has already been dubbed the tear-free onion. But, said O'Connor, it has been bred using conventional methods, and should not be confused with genetically engineered product developed in Japan.

Supasweet appeared at Sainsbury's and Safeway last year and both stores have been involved in the development programme and enjoyed exclusivity. Although Safeway has since discontinued the line, Waitrose, Tesco and Budgens have all now been given access.

The product appears in stores in both pre-pack and loose formats and both lines feature the Supasweet sticker.