Horticultural activists traded thousands of illegal seeds in protest at the corporate control of the market.

More than 1,000 eco-rebels packed the Old Market in Hove for Seedy Sunday.

They swapped outlawed seeds such as cocoa bi-colour climbing bean and Lazy Housewife french beans.

Organiser, Vanessa Tourle, 32, of Richmond Road, Brighton, said: "It's my favourite day of the year. It's an up-yours to the big companies.

"I love all the different groups coming together. Everybody has the same viewpoint about why they're doing it to save the seeds."

Swapping seeds is a passion for growers and anti-corporate protesters as they attempt to save varieties of seed from the clutches of big business.

Just three corporations control a quarter of the world's seed market and have been accused of allowing unusual varieties to die out.

It is estimated that 97 per cent of vegetable varieties have been lost in the past 100 years.

Swappers get around the illegality of selling their seeds by swapping them or accepting donations.

So far there have been no prosecutions in Britain, although growers have come under legal pressure in America and France.

Organiser Kim Turner, 48, of Islingword Road, Brighton, said: "If you look at Ireland, they were only growing two varieties of potato when the famine happened. If they had grown more, they may have survived.

"Monoculture is the enemy."

The city's annual family-friendly fest, sponsored by Infinity Foods, attracts allotment growers and community groups from far afield. This pioneering seedswap has since spawned another 20 around the country.

Another organiser Fran Saunders, 52, of Loder Road, Brighton, said: "It has spread like dust in the wind.

"About 400 people came to the first one in Kemp Town but we outgrew it.

" It's about a collective of people who chip in and do various bits for free to create a really dynamic, vibrant day."

When they weren't busily pouring seeds into packs and swapping potatoes for pumpkins, visitors were trying organic cooked food provided by Due South.

Ade Lovejoy, 35, of Bristol Gate, Brighton, said: "It's really important having food at events like this, because it's all about bringing people together and food's a really good example of that.

"It's all organic and locally sourced which is important because of the pollution cost of bringing it over. It also supports local communities which is what the whole thing's about.

"It's such a social event. Anyone who's anyone involved in food is here and what a good place to be if you're into food and gardening."

A series of talks also took place throughout the day. Subjects included corporations and farming, the history of agriculture and tips on organic gardening.

Record numbers now care about where food comes from, with 28 per cent of us boycotting groceries for ethical reasons in 2004, according to the ethical consumerism report last year by The Cooperative Bank.

A BBC crew were at the event to make a documentary for Radio 4 about the corporate patenting laws which inspired this underground movement.