| Contracting Parties/Signatories | Signature | Instrument | In Force | Details |
| Brunei Darussalam | December 15, 1987 | Ratification: June 28, 1988 | August 2, 1988 | |
| Indonesia | December 15, 1987 | Ratification: April 30, 1999 | May 29, 1999 | |
| Lao People's Democratic Republic | December 15, 1987 | Ratification: July 25, 1988 | August 2, 1988 | |
| Malaysia | December 15, 1987 | Ratification: July 23, 1997 | August 21, 1997 | |
| Philippines | December 15, 1987 | Ratification: January 27, 1988 | August 2, 1988 | |
| Singapore | December 15, 1987 | Ratification: January 24, 1989 | February 22, 1989 | |
| Thailand | December 15, 1987 | Ratification: June 17, 1988 | August 2, 1988 | |
| Viet Nam | | Accession: August 16, 1996 | September 14, 1996 | |