At the same time, the committee removed the walled city of Baku from the endangered list, and added more sites to its catalog of global heritage.
Mangrove cutting and excessive development is the main problem in the Belize Barrier Reef Reserve System, which was inscribed on the UNESCO World Heritage List in 1996 as the largest barrier reef in the northern hemisphere, the committee said.
It comprises offshore atolls, hundreds of sand cays, mangrove forests, coastal lagoons and estuaries.
UNESCO said it placed Colombia's Los Katios National Park on the Danger List at the request of Bogota "so as to help mobilize international support for the preservation of the property."
New historical sites
The committee, which has been meeting since Monday, has also named new sites across the globe to UNESCO's World Heritage List.
They include in Asia’s sacred mountains in China and Kyrgyzstan, and the royal tombs of the Joseon dynasty in South Korea, and in the Middle East an ancient water system near the Iranian city of Shushtar.
Africa Cape Verde's 15th century town of Cidade Velha and Burkina Faso's Loropeni ruins join the list.
New European sites include Italy's Dolomite Mountains, and the tidal flats and wetlands of the Wadden Sea in Germany and the Netherlands.
A committee spokeswoman said Saturday that the century-old Stoclet Palace, a luxurious private house in Brussels designed by Austrian architect Joseph Hoffmann, had also been added.
It also inscribed the Tubbataha Reefs Natural Park in the Philippines as an "extension" to the Tubbataha Reef Marine Park, which joined the World Heritage List in 1993. The UN Educational, Scientific and Cultural Organisation's heritage list now comprises some 885 sites that have "outstanding universal value."
The committee praised the success of authorities in Azerbaijan in rescuing the Baku walled city along with the Shirvanshah's palace and the Maiden Tower, which had been placed on the endangered list in 1993.