On behalf of 25,000 members in the scientific community, many of whom are responsible for conducting the trials, the union said that a debate without informed scientific fact amounted to little more than a public relations exercise.

Nigel Titchen, President of the union’s Science, Engineering and Technology group, said: "Prospect neither supports nor opposes genetically modified crops. As scientists, we see our role as honest brokers of information. But it is impossible to have an open, public debate when the crops have not yet been harvested and the facts are not available.

"This debate has been over two years in the making and it would be a grave mistake if the only scientific study of what actually happens when GM crops are grown in Britain does not form part of it."

The union is calling for a second round of talks to take place in September after the findings of the field trials, currently taking place at over 250 sites, have been published.

The subject is one of a number of topics scientists will debate today at the annual delegate conference of the union’s Science, Engineering and Technology group, taking place at the National Liberal Club, London.