The Federation of Tour Operators is sending a UK medical expert to the Dominican Republic where dozens of UK holidaymakers have reportedly been struck down by a stomach bug.
A number of customers staying at the Hotel Bahia Principe, in the resort of Rio San Juan, have had sickness and diarrhoea.
The FTO said it is working with the hotel management and tour operators to deal with the situation.
Both First Choice and Thomas Cook have guests staying in the resort.