The scientists behind an explosive new study on the health effects of a leading weedkiller and a strain of genetically-modified maize have come in for a barrage of criticism.

Yesterday a French research team claimed exposure to the herbicide Roundup – produced by biotech giant Monsanto – caused tumours to develop in lab rats and led to premature death. It also linked tumours and organ damage with exposure to the NK603 strain of Roundup-resistant GM maize also developed by Monsanto.

But critics have called into question the reliability of the study’s findings, raising concerns over the sample size of the rats tested and whether the restrictions placed on the control group’s diet were sufficiently robust. Critics also highlighted the rats’ high natural susceptibility to tumours.

The Agricultural Biotechnology Council - a pro-GM body representing biotech companies - led the criticism.

“The plant biotechnology industry takes all health concerns regarding biotech food and feed very seriously and is committed to the highest standards of testing and safety for its products,” said ABC chairman Dr Julian Little.

“Biotech crops are among the most extensively tested foods in the history of food safety. In 2011, the European Commission released a compendium of 50 research projects on the safety of GMOs over the last decade. The Commission funded research from 130 research project involving 500 independent research groups over 25 years, concluding that ‘There is, as of today, no scientific evidence associating GMOs with higher risks for the environment or for food and feed safety than conventional plants and organisms.’

“An estimated two trillion meals containing GM ingredients have been eaten around the world over the last 13 years without a single substantiated case of ill-health. The World Health Organisation has said that: ‘No effects on human health have been shown as a result of the consumption of such foods by the general population in the countries where they have been approved’.

“Studies by Seralini [the report’s lead author] and his fellow anti-GM campaigners have in the past not withstood peer review, including criticism from the European Food Safety Authority, Food Standards Australia New Zealand, and the Public Research & Regulation Initiative (PRRI), a world-wide initiative of hundreds of public sector scientists.”

The EFSA said it was aware of the new study. “We will consider the paper’s relevance, taking into account the available scientific evidence including recent studies assessing, over a sustained period of time, the potential toxicity of foods derived from GM crops,” the body said.

Despite the controversy, campaigners said the study raised important questions about food safety.

“It is time for the EU to act to protect public health,” said Mute Schimpf, food campaigner for Friends of the Earth Europe. “On the basis of this research, national governments and the European Commission should immediately suspend all similar GM foods and halt all further GMO approvals.”

A spokesman for Monsanto said the company would “review [the study] thoroughly, as we do all studies that relate to our products and technologies”.