The UNWTO said while efforts to restart tourism had so far had been "slow but continuous", it was vital the world reopened in a responsible manner.
Its latest data shows that by 19 July, 40% of destinations had eased restrictions, up from 22% as of 15 June and 3% as of 15 May.
"It confirms the trend of a slow but continuous adaptation and responsible restart of international tourism," said the UNWTO.
However, only four of the 87 destinations that have eased their Covid measures have lifted restrictions altogether.
The UNWTO’s latest data also shows 115 destinations worldwide – more than half – still have their borders shut to tourists.
“The restart of tourism can be undertaken responsibly and in a way that safeguards public health while also supporting businesses and livelihoods," said UNWTO general secretary Zurab Pololikashvili.
"As destinations continue to ease restrictions on travel, international cooperation is of paramount importance.
"This way, global tourism can gain people’s trust and confidence, essential foundations as we work together to adapt to the new reality we now face.”
Its latest report, the UNWTO found destinations with higher dependency on tourism were more likely to be easing travel restrictions.
Of the 87 destinations that have eased restrictions recently, 20 are small island developing states, many of which depend on tourism as a central pillar of employment, economic growth and development.
The report also reveals around half (41) of all destinations that have eased restrictions are in Europe, which the UNWTO said confirmed the "leading role" the region would play in encouraging a responsible restart of tourism.
Many destinations though look set to remain in longer-term lockdown; 88 of the 115 that have completely closed their borders to international tourism have been shut for more than 12 weeks.
The UNWTO estimates that by he end of May, the pandemic has already resulted in $320 billion in lost revenue, three times the cost of the 2009 global economic crisis.
