Previous research has suggested a link between the two conditions, but they have never compared their studies against a control group.

This means they could not calculate how great the risk was.

Now Spanish researchers have compared 318 people with gastroenteritis with more than 500,000 members of the public.

After a year, they found that 0.3% of the public developed irritable bowel syndrome (IBS), compared with 4.4% of the people who had had bacterial gastroenteritis.

Food poisoning

They calculated that the risk is up to 10 times greater for people who have had bacterial gastroenteritis, caused by infections such as Salmonella and Campylobacter.

Writing in the British Medical Journal, they say: "We conclude that bacterial gastroenteritis is a major independent risk factor for irritable bowel syndrome."

IBS is fairly common and is not life-threatening. However, it can cause discomfort and, in people who suffer badly from it, it can be disabling.

It leads to crampy pain, gassiness, bloating, and changes in bowel habits.

There is no cure, but doctors suggest diet changes and stress management can help.

Risk surprise

Dr Luis Garcia Rodriguez, one of the Spanish doctors, told BBC News Online he had not expected such findings.

"We expected to see a greater risk, but we were surprised at how great the risk was," he said.

He thinks the link is due to either the gastroenteritis not being totally cured or because the bacteria has altered the body's balance.

If the former is the case, it could mean that stronger antibiotics are needed to treat the gastroenteritis, said Dr Garcia Rodriguez.

The research paper is part of a larger study of the effect of antacid drugs on bacterial gastroenteritis.

Dr Garcia Rodriguez hopes the research will be taken on and more studies conducted to find out what causes the link.

But he stressed that, despite the link, only about one in 20 people who have gastroenteritis are likely to develop IBS.