A group of more than 60 protesters descended on the gates of the John Innes Centre in Norwich today as part of a campaign against genetically modified potatoes.

Carrying banners saying 'stop gambling with our chips', the group met at The Forum before travelling down The Sainsbury Laboratory, near the Norfolk and Norwich University Hospital, by bike or marching in a group.

At the heart of the protest was a tractor pulling 20kg of organic potatoes that were left at the centre.

People had travelled from London, Yorkshire, Scotland, Wales and even France to be a part of demonstration against scientists' work to trial blight-resistant GM potatoes.

They said that there are six natural varieties that are already blight-resistant, making this publically-funded work 'absurd'.

The group claim that researchers at the laboratory have spent �1.7m trying to develop a potato resistant to the fungal disease, but the centre said this money has been spent across five project, with much of it on fundamental research not related to this trial.

Farmer Gerald Miles, of Pembrokeshire, drove a tractor to the front of the centre's gates, before the 40 boxes of organic potatoes were left at there and under the entrance sign.

Mr Miles, 63, said that the blight-resistant organic Sarpo Mira variety from Hungary he had with him were 'really wonderful'.

He said: 'In the past I have grown 50-60 acres of potatoes for 40 years. I think this is absolutely a big stepping stone in farming and am appalled we are wasting money and research in trying to create a genetically modified blight resistant potato when we already have six varieties.'

At the protest was former organic farmer Peter Reeve, of Robertson Close, Sheringham, who said he was very interested in Mr Miles' farming of these varieties.

Mr Reeve, 80, said that serious questions had to be asked about the long time potential impacts of genetic modification.

He said: 'I accept there is good science going into this but very valid questions have to be asked and they can't be brushed off. The science and research need to be better.'

Professor Jonathan Jones, of the centre, said that the idea of replacing the current industrial agriculture with the organic potatoes was 'never going to happen'.

He said that these organic variety of potatoes were not popular with consumers but said he was closer to the protesters way of thinking than they thought. He said that the GM potatoes would help the environment as they would reduce CO2 emissions as they would not need to be sprayed with pesticide so often.

'We all want to reduce the environmental impact of agriculture,' he said.

The centre says that UK farmers spend an average of �60m a year controlling blight, with worldwide losses of approximately �3.5bn.

The protest was watched by a significant police presence, with groups of officers at every gate and a police helicopter.

Mr Jones said: 'It is unfortunate that there is a big cost of police time and the reason is that we tried to engage with the protesters and find what they wanted, but weren't able to get them on the phone, only emails, so we didn't know many people would show up and did not have reassurances there wouldn't be vandalism.'

A spokesman for the police said the protest passed peacefully.