Medical scientists and environmental health officers in Galway will continue testing today to try to establish the cause of a dramatic rise in severe stomach illnesses which is affecting people in the city and county.

There were fears that the illness, which causes severe cramps and diahorrea, was being transmitted by water supplies.

Over 90,000 living in the city and in an area of the county between Moycullen in Connemara and Tuam and Athenry are being advised to continue boiling tap water before drinking it or using it for food preparation.

Experts at the regional pathology laboratory say they still have not been able to establish the cause of the outbreak, but they will be continuing to examine samples which local GPs have been sending them in recent days.

The city and county council and the HSE West are involved in a testing and monitoring operation.