According to the Article XIII of the Treaty Of Izmir, “Any State enjoying geographical contiguity with the ECO region and/or sharing the objectives and principles of ECO may apply to become a member of the Organization.” Currently ten countries from West and South Asia, Caucuses and Central Asia are Members of the Economic Cooperation Organization.
| States | Signature | Ratification | |
 |
Islamic Republic of Afghanistan | Yes | Yes |
|
|
Republic of Azerbaijan | Yes | Yes |
 |
Islamic Republic of Iran | Yes | Yes |
 |
Republic of Kazakhstan | Yes | No |
 |
Kyrgyz Republic | Yes | Yes |
 |
Islamic Republic of Pakistan | Yes | Yes |
 |
Republic of Tajikistan | Yes | Yes |
 |
Republic of Turkey | Yes | Yes |
 |
Turkmenistan | No | No |
 |
Republic of Uzbekistan | No | No |
OBSERVER STATE
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Turkish Republic of Northern Cyprus |