A reading above 50 represents expansion while one below means contraction.
A reading above 50 indicates expansion while a one below this level means contraction.
Service providers' confidence with regard to the 12-month outlook for business activity remained positive.
Manufacturing production growth eased in May, which combined with the slowdown in services resulted in a weaker increase in private sector output, the survey said.
On the employment front, services employment was unchanged in April.