As a result of the "robust" performance, the organisation said it was boosting its 2013 forecast. After originally tipping growth of three-four percent for the whole year, it now expected the increase to be at the higher end of that range "or to slightly exceed it".
Europe enjoyed growth of 5.1 % in international tourist numbers in the six months, it said.
Asia and the Pacific reported growth of 6.2 % including an 11.6-% surge in tourists going to Southeast Asia.
But results were weaker than anticipated in the Americas, which posted growth of just 2.2 %.
International tourist numbers grew 3.1 % in North America but South America reported growth of just 0.3 % and the Caribbean had growth of a meagre 0.1 %.
In Africa, international tourist arrivals rose by 3.8 %.
In the Middle East, tourist numbers soared by 12.9 % but these figures should be viewed "with caution" because of uneven results and limited data, the group said.