Genetically modified (GM) crop trials could create new incurable diseases and destroy people's immune system, activists are warning.

The Munlochy GM Vigil Group wants MSPs to impose a moratorium on future tests as a precautionary measure rather that "take risks on human health".

The group and other anti-GM activists delivered their plea to a Holyrood committee at the starts of an inquiry into the health impact of GM crops.

But the company behind the Scottish trials, Bayer CropScience, insists that there is no evidence "of a significant risk to humans or livestock" from eating GM crops.

Munlochy protesters have been arrested

The Scottish Parliament's Health Committee started its inquiry into the public health implications of GM trials on Wednesday.

One group giving evidence - the Munlochy GM Vigil - has collected over 6,500 signatures in protest at trials at Munlochy on the Black Isle.

Spokesman Anthony Jackson criticised the tests carried out by biotech companies as inadequate and demanded tougher checks similar to those for new pesticides and food additives.

He said: "We are asking for more science and more research of a rigorous nature, and until then there should be a moratorium on GM crops and food."

"There is no demand for GM produce, hence there is no need to take risks on human health.

'No significant risk'

"We should not repeat historical mistakes where commercial power took precedence over the precautionary principle."

Representatives from biotech firm Bayer CropScience were scheduled to give evidence to the committee but postponed their appearance due to illness.

In a written submissions to MSPs the company insists that there is "no evidence whatsoever of a significant risk to humans or livestock" from eating GM crops.

It said: "The genetic modifications themselves have been the subject of intense scrutiny and the nutritional quality of the rape seed has been demonstrated to be as high as that of non-GM products."

The Health Committee agreed to set up an inquiry in September after receiving a report from committee member and SNP shadow health minister Nicola Sturgeon.