Kingsbury Water Park in Warwickshire has been closed while the investigation takes place.

Four visitors in four days suffered an extremely rare allergic reaction. Three needed hospital treatment.

Experts believe the insect responsible for the four cases of anaphylactic shock could be a black fly, although attempts to confirm the theory are continuing.

Site survey

The local authority said the popular beauty spot has been closed indefinitely as a precautionary measure.

A Warwickshire County Council spokesman said representatives from the authority, Warwickshire Health Authority's public health department and North Warwickshire Borough Council's environmental health department were assessing the problem.

"Given that a fourth case had occurred on Sunday elsewhere in the park, a decision was made to close the park to enable further investigations into the source of the bites," the spokesman said.

"The county entomologist is surveying the site to try and identify what species of insect is causing the problems.