The move marks the latest advance in the emerging field of molecular farming, which may offer a cheaper way of making biotech drugs and vaccines than traditional factory systems.

European researchers said on Thursday they had produced tobacco plants containing a potent anti-inflammatory protein called interleukin-10 (IL-10) that could help patients with insulin-dependent type 1 diabetes and other autoimmune diseases.

A number of agrochemical companies, including Bayer and Syngenta, have been looking at ways to make complex protein drugs in plants, although progress has been slow.

At the moment, antibody medicines and vaccines are produced in cell cultures inside stainless steel fermenters.

However, Mario Pezzotti of the University of Verona, who led the tobacco study published in the journal BMC Biotechnology, believes they could be grown more efficiently in fields, since plants are the world's most cost-effective protein producers.

Several different plants have been studied by research groups around the world, but tobacco is a firm favourite.

"Tobacco is a fantastic plant because it is easy to transform genetically and you can easily regenerate an entire plant from a single cell," Pezzotti said in a telephone interview.

His group's work has attracted interest from tobacco giant Philip Morris, which is supporting a conference on plant-based medicine in Verona in June.

Pezzotti and colleagues – who received funding for their research from the European Union – now plan to feed the plants to mice with autoimmune diseases to find out how they respond.

Further down the line, they want to test whether repeated small doses could help prevent diabetes in people, when given alongside another compound called glutamic acid decarboxylase (GAD65), which has also been produced in tobacco plants.

Swedish biotech company Diamyd is already testing a conventionally produced GAD65 vaccine against diabetes in clinical trials.

Molecular farming has yet to yield its first commercial product, although Israel's Protalix BioTherapeutics is conducting advanced clinical tests on an enzyme treatment for Gaucher disease that is produced in a culture of carrot cells.