The number of international tourist arrivals grew 7% in 2017 to 1.3 billion, according to latest estimates.
It said this “strong momentum” was expected to continue in 2018, with a growth rate of between 4% and 5%.
UNWTO said definitive figures would not be published until the spring.
In 2016, both the US and Spain received around 76 million international visitors, but last week Spanish PM Mariano Rajoy said the country had a record year in 2017, with more than 82 million international visitors – a year-on-year leap of almost 8%.
In its preliminary analysis of 2017 tourism data, UNWTO said: “Led by Mediterranean destinations, Europe recorded extraordinary results for such a large and rather mature region.”
Europe saw an 8% increase in international arrivals during the year, as did Africa. Asia and the Pacific recorded growth of 6%, the Middle East 5% and the Americas 3%.
Tourism was boosted by a global economic upswing, and a rebound in spending from Brazil and the Russian Federation after some years of decline.
“International travel continues to grow strongly, consolidating the tourism sector as a key driver in economic development,” said UNWTO chief Zurab Pololikashvili.
“As the third export sector in the world, tourism is essential for job creation and the prosperity of communities around the world.”