| Country | Action | Action Date | Effective Date |
|---|
| AUSTRIA | Signature | 05/08/1955 | |
| BELGIUM | Signature | 05/08/1955 | |
| BELGIUM | Ratification | 12/05/1965 | |
| DENMARK | Signature | 05/08/1955 | |
| FRANCE | Signature | 05/08/1955 | |
| GERMANY FEDERAL REPUBLIC | Signature | 05/08/1955 | |
| GREECE | Signature | 05/08/1955 | |
| ICELAND | Signature | 05/08/1955 | |
| IRELAND, REPUBLIC OF | Signature | 05/08/1955 | |
| ITALY | Signature | 05/08/1955 | |
| LUXEMBOURG | Signature | 05/08/1955 | |
| NETHERLANDS THE | Signature | 05/08/1955 | |
| NETHERLANDS THE | Ratification | 28/01/1958 | |
| NORWAY | Signature | 05/08/1955 | |
| PORTUGAL | Signature | 05/08/1955 | |
| SPAIN | Accession | 20/07/1959 | |
| SWEDEN | Signature | 05/08/1955 | |
| SWITZERLAND | Signature | 05/08/1955 | |
| SWITZERLAND | Ratification | 27/10/1955 | |
| TURKEY | Signature | 05/08/1955 | |
| UNITED KINGDOM | Signature | 05/08/1955 | |
| UNITED KINGDOM | Ratification | 26/07/1960 | |