Targeting the Boston Marathon was "all the more appalling for taking place at an event renowned for bringing people together from around the world in a spirit of sportsmanship and harmony", he added.

BBC: Boston blasts: World reaction

Servas, generally regarded as the earliest hospitality exchange, was founded, in 1949, as a means of promoting world harmony (its original name was Peacebuilders).

NEWYORKER: You��re Welcome

Let us hope it will also be a force for peace and harmony in a world that is clearly headed for a new, vigorous and provocative pluralism of values, cultures and civilizations.

CNN: Building On A Golden Age

It has been held every year since 1947 - when it was set up as a means of promoting international harmony in the wake of the Second World War.

BBC: Visa hitches threaten eisteddfod