The genetically modified (GM) food debate flared up again as it was reported that U.K. scientists have developed a new genetically-modified strain of "golden rice," which produces more beta-carotene than before.

The strain produces around 20 times as much as previous varieties, the BBC reported.

The human body converts beta-carotene into vitamin A, and the breakthrough could help reduce deficiency of the vitamin and childhood blindness in developing countries, the report said.

The new variety has been developed at the U.K. laboratories of the biotechnology company Syngenta. No one was available at the company to comment.

Friends of the Earth GM campaigner Clare Oxborrow told the Press Association, "One of our concerns is that the golden rice only addresses a very small part of a very big problem.

"Vitamin A deficiency and the blindness that results from it is a huge problem in developing countries.

"However, the cause of it is not just the fact that rice is deficient in vitamin A; it is that the underlying poverty and malnutrition causes people to be deficient in a whole range of nutrients, including vitamin A.

"For people to absorb and use the vitamin A from the golden rice, they would need to have a lot of other nutrients in their diet, such as zinc.

"We want to see more political will addressing the underlying causes of poverty and malnutrition, and focusing on trying to encourage people to grow a diverse range of fruit and vegetables."

She added that it would be important to test the product to a very high standard for safety.

"Another of our concerns is that golden rice has been in the development stage for years, a lot of time and money has gone into this, and we still haven't got a product that is safe and ready to use.

"It has to go into safety testing, and we want to see the most rigorous safety testing of this product."

The BBC said Syngenta would make the rice available for free to research centers across Asia, who will, if they are given the go-ahead by their governments, begin field trials.