Spanish vegetables, many of which end up on British dinner plates, are being watered with untreated sewage in parts of Spain as farmers battle to raise crops in a severe drought according to The Guardian.

The environment minister, Cristina Narbona warned cabinet ministers that more farmers in the vegetable-growing region of Murcia would use untreated sewage if clean irrigation water were not made available "When they don’t get irrigation water, they turn to other kinds of water."

Britain’s Food Standards Agency confirmed yesterday that an outbreak of the resistant form of salmonella, Typhimurium DT104, in January had been linked to imported Spanish vegetables. "The source seemed to be iceberg lettuce from the Murcia region," a spokesman said.

The 96 reported cases were more than three times the norm for this kind of salmonella in Britain, and of the 90, 11 people needed hospital treatment. In Finland, there have been 56 cases of salmonella compared with an annual average of three.

It was unclear yesterday whether there was any scientific evidence to back Ms Narbona’s link between health problems abroad with the use of untreated sewage. "The limited outbreaks observed to date suggest that only a small proportion of lettuce was contaminated," the Finnish health authorities noted, however  the Food Standards Agency yesterday advised cooks to wash lettuce, wherever it came from.