Translate the following English sentence to French:
"The Commission feels that any lasting solution will require a genuine immigration policy to be gradually established. This policy must take account of the Union' s views on social, economic and demographic developments, and will consequently guarantee the admission of migrants under an organised and clear framework, as well as their harmonious integration into the communities that receive them."
Toute solution durable passe, de l'avis de la Commission, par la mise en place progressive d'une véritable politique de l'immigration qui, s'inscrivant dans les perspectives de développement social, économique et démographique de l'Union, assure l'admission de migrants dans un cadre ordonné et clair, ainsi que leur intégration harmonieuse dans les communautés d'accueil.