The five year agreement, which will automatically be extended for subsequent periods of one year unless blocked, was signed by Alfredo Pérez Rubalcaba, Spain's interior minister, and Michael Dodman, the chargé d'affaires of the US mission to the EU.

It still needs to be approved by the European Parliament, which rejected a provisional agreement between the EC and the US in a vote in February.

However, Liberal MEPs are expected to back the latest offering which assigns Europol the role of verifying that data requested by the US is needed for tracking terrorism. It also gives Europeans the right to block transfers of their personal data.