European Convention on Access to Official Documents
In 2009 the Council of Europe passed its first ever Convention on Access to Official Documents. It was agreed upon in the Norwegian town of Tromsø and thus also bears the name Tromsø-Convention or Convention 205.
Before entry into force it needs 10 ratifications. See the list of signatories and ratifications here.
"This Council of Europe Convention is the first binding international legal instrument to recognise a general right of access to official documents held by public authorities. (...)This Convention lays down a right of access to official documents. Limitations on the right of access to official documents are only permitted in order to protect certain interests like national security, defence or privacy," according to the summary of the text.