Myanmar was in breach of the Chemicals Weapons Convention of banning chemical weapons and may have a stockpile leftover from the 1980s, said a senior official of US State Department at the organization's annual meeting for the Prohibition of Chemical weapons.
"The US has serious concerns that a chemical weapons stockpile may remain at Myanmar's historical chemical weapons facility," Thomas DiNanno, Deputy Assistant Secretary of State, told the Organization of the Prohibition of Chemical Weapons on Monday.
Based on available information, the United States certifies that Myanmar is in noncompliance with the CWC, due to its failure to declare its past chemical weapons program and to destroy its chemical weapons facility, AFP reports.
However, Myanmar officially joined the Chemical Weapons Convention (CWC), which bans the production, storage and use of chemical arms in 2015.
Myanmar was the 191st State Party to the Chemical Weapons Convention, which came into force in 1997 and is monitored by the OPCW for compliance.
Previously, Myanmar has faced accusations of storing and using such weapons.
In 2005, London-based rights group Christian Solidarity Worldwide accused the former military junta of using chemical weapons against rebels from the Karen community.
In 2013, a parliamentary report said police had used phosphorus the previous year against protesters at a copper mine in the north of the country, causing severe burns.
In July 2014, five journalists from Myanmar were sentenced to 10 years in prison with hard labour over an article accusing the military of producing chemical arms.
The US official said Washington had held talks with Myanmar's civilian government and military over the issue and "stands ready to assist Myanmar" to destroy the weapons.
The US allegation comes as Myanmar faces growing international legal pressure over its treatment of another minority — the Muslim Rohingya, thousands of whom were forced to flee to Bangladesh in a huge military operation in 2017.
Civilian leader Aung San Suu Kyi is due to travel to the International Court of Justice in The Hague in December to lead the defense in a genocide case against Myanmar.