International distribution and outsourcing firm Bunzl said third quarter revenue increased 6% year-on-year on a constant exchange rate basis as acquisitions came on stream.This was thanks in large part due to underlying growth of approximately 3% and the positive impact from 13 acquisitions so far this year.The group also announced the purchase of Holland-based firm De Ridder Groep BV, a distribution business engaged in the supply of products to prisons, police stations and other detention centres."The acquisition of De Ridder further extends our business in the Netherlands and we are delighted to welcome their employees to the Bunzl group," said group chief executive Michael Roney."We have acquired 13 businesses so far this year and, with ongoing discussions taking place with a number of targets, we would expect to complete further acquisitions before the year end."