UNITED NATIONS (Reuters) - Syria became a full member of the global anti-chemical weapons treaty on Thursday, the country's U.N. envoy said, a move that the government of Syrian President Bashar al-Assad had promised as part of a deal to avoid U.S. air strikes.

"Legally speaking Syria has become, starting today, a full member of the (chemical weapons) convention," Syrian U.N. Ambassador Bashar Ja'afari told reporters in New York after submitting relevant documents to the United Nations.

Syria was one of only seven countries not to have joined the 1997 Chemical Weapons Convention, which commits members to completely destroying their stockpiles.

(Reporting by Michelle Nichols; Editing by Eric Beech)