The BBC's Pallab Ghosh reports on the genetic food dispute

The public statement from 20 scientists has renewed calls for the UK Government to impose immediately a moratorium on the use of genetically-modified (GM) foods.

However Prime Minister Tony Blair has rejected the calls from consumer, environmental and food pressure groups, as well as opposition politicians.

Jack Cunningham: "A moratorium is neither necessary nor possible"

Cabinet Office Minister Dr Jack Cunningham said the findings "were in dispute" and that a moratorium would not be "sensible".

He told the BBC: "We need to clarify what the scientific outcome of these experiments really is. But it is not a reason to ban all genetically-modified foods."

Support for doctor

GM crops: Moratorium requested

The controversy began in August 1998 when Dr Arpad Pusztai, 68, made a public statement about his fears, following a £1.6m study he conducted at the Rowett Research Institute (RRI) in Aberdeen, Scotland.

He told Granada's World in Action that he would not eat the GM food and said it was "very, very unfair to use our fellow citizens as guinea pigs".

Within 48 hours he was suspended in humiliation and later effectively forced to retire. The RRI said he had misinterpreted his results.

But now the group of scientists, drawn from 13 different countries, have re-examined his work and signed a joint memorandum saying his conclusions were justified. The group included toxicologists, genetic engineers and medical experts.

Dr Vyvyan Howard: "We are going to have to test these plants like pharmaceutical agents"

"We found that his data is sound", their spokesman, Dr Vyvyan Howard, a toxipathologist at Liverpool University, told the BBC.

He said: "Dr Puztai did some direct hazard assessment, got some unexpected results and then spoke out. I think he was right."

Dr Howard said a new safety regime was needed: "We're going to have to test these plants like pharmaceutical agents. This takes years and costs about $400m to bring a new drug to market because of the level of testing."

However Professor Phillip James, director of RRI, stuck by his actions over Dr Putzai, saying the research was incomplete and unchecked.

Immune system and organ damage

Dr Pusztai's experiments involved feeding rats on GM potatoes for 10 days. He found that some of the rats' immune systems were weakened.

He also found that some organs shrank or did not develop properly, including the kidney, the spleen and the brain.

The cause of these problems is not known and the group of scientists has demanded immediate funding to investigate.