Some 28 people have fallen ill so far this year after eating poisonous mushrooms they had picked themselves, more than double the number reported at the same time last year, the information centre for poisonous substances NVIC has said.

A hot summer followed by rain has created the ideal circumstances for an explosion of mushrooms this year. The NVIC said some people had developed very serious symptoms, such as liver failure on consuming the mushrooms.

The organisation said that many of the people reported to have been poisoned had a non-Dutch background. It speculated that they were perhaps used to picking mushrooms in their own countries and that they could be unfamiliar with the types of mushroom that grow in the Netherlands, some of which are highly toxic.

The most lethal of the Dutch mushrooms are the amatoxin-containing species, such as the Amanita phalloides. It causes diarrhea and vomiting 6 to 24 hours after consumption. The patient then seems to recover but meanwhile the toxins are attacking the liver which can result in liver failure and death if not treated in time.