Food manufacturers have been urged to re-consider their packaging methods for products such as breakfast cereal, after researchers in Switzerland raised concerns about the possible health risks of recycled cardboard.

The Food Safety Laboratory in Zurich found that mineral oils in printing ink from recycled newspapers used in cardboard can get into foods such as cereal, pasta and rice - even passing through protective inner plastic bags.

Spokesman Koni Grob said toxicologists had linked the oils to inflammation of internal organs and even cancer, though he stressed that individual meals would contain only a tiny dose of the chemicals.

He said switching to non-recycled packaging was too costly in terms of the environment and new solutions needed to be considered such as inner food linings which act as effective barriers to the oils.

He stressed that research had found products such as paper and bags made of polyethylene and polypropylene are ineffective as a barrier from mineral oils although aluminium foil was effective.