| Country | Action | Action Date | Effective Date |
|---|
| AUSTRIA | Signature | 27/03/1961 | |
| AUSTRIA | Ratification | 26/06/1961 | |
| DENMARK | Signature | 27/03/1961 | |
| DENMARK | Ratification | 29/05/1961 | |
| FINLAND | Signature | 27/03/1961 | |
| FINLAND | Ratification | 23/05/1961 | |
| ICELAND | Accession | 22/01/1970 | |
| LIECHTENSTEIN | Ratification | 26/06/1961 | |
| NORWAY | Signature | 27/03/1961 | |
| NORWAY | Ratification | 19/06/1961 | |
| PORTUGAL | Signature | 27/03/1961 | |
| PORTUGAL | Ratification | 26/06/1961 | |
| SWEDEN | Signature | 27/03/1961 | |
| SWEDEN | Ratification | 02/06/1961 | |
| SWITZERLAND | Signature | 27/03/1961 | |
| SWITZERLAND | Ratification | 22/06/1961 | |
| UNITED KINGDOM | Signature | 27/03/1961 | |
| UNITED KINGDOM | Ratification | 09/06/1961 | |