UNITED NATIONS, April 26 (Xinhua) -- UN Secretary-General Antonio Guterres on Wednesday warned that progress made in eliminating the world's declared stockpiles of chemical weapons is threatened by belligerents in the Middle East.

"The recent attack in Syria was a horrific reminder of the stakes," the secretary-general said in a video message to the commemorative ceremony for the 20th anniversary of the Chemical Weapons Convention and the Organization for the Prohibition of Chemical Weapons (OPCW), which is held in The Hague, the Netherlands.

"Nearly all countries are party to the convention -- and the Organization has helped eliminate most of the world's declared stockpiles," the secretary-general said. "But progress is under threat."

"In the Middle East, belligerents are breaking the norm against chemical weapons," Guterres said.

The OPCW is the implementing body of the convention, which entered into force in 1997. As of April 26, 2017, the OPCW has 192 member states, who are working together to achieve a world free of chemical weapons.

Meanwhile, the secretary-general voiced his hope that all countries will support the OPCW's critical fact-finding mission, as well as its joint investigative mechanism with the United Nations.

While the convention and the implementing body celebrate two decades of success, Guterres said, "Now, let us renew our resolve to consign these diabolical weapons to the pages of history."

The commemorative ceremony was attended by 450 permanent representatives and other delegates from the OPCW member states, chemical weapon victims, leaders of international organisations, chemical industry and civil society; and dignitaries from the Netherlands.

As the implementing body for the Chemical Weapons Convention, the OPCW oversees the global endeavour to permanently and verifiably eliminate chemical weapons. Since the convention's entry into force in 1997 -- and with its 192 States Parties -- it is the most successful disarmament treaty eliminating an entire class of weapons of mass destruction.

Over the past 20 years, nearly 95 percent of chemical weapon stockpiles declared by possessor states have been eliminated under the watchful eye of the OPCW. One hundred and ninety-two countries committing themselves to the Chemical Weapons Convention have made it possible for 98 percent of the global population to live under the convention's protection.

This achievement is the result of a global endeavor -- involving nations, chemical industry, scientists, and civil society -- to create and enforce the world's most successful international disarmament treaty.