With the world shocked by rising food prices, and millions in the developing world struggling to get enough to eat, the problem of food security is right back on the world's agenda.

And with the world's population likely to rise to nine billion in the next few decades, feeding the world is going to become an ever-greater problem.

Are transgenic crops the answer to the problem, or do they, as Prince Charles has argued, threaten an environmental catastrophe?

What's the evidence on the success or failure of GM to date?