Sir

As the president of the executive commission of the proposed European Spallation Source (ESS) neutron-science facility in Bilbao, Spain, I appreciate the comments in your Editorial 'The big picture' (Nature 450, 586; 2007) about European endeavours to construct and finance the ESS. Although the commission acknowledges that there is a tendency in other countries to use European funds to finance such scientific projects, this does not apply in our case.

The joint bid by Spain and Hungary does not propose the use of European funds for this purpose. Our intention is simply to work together to facilitate approval for the construction of this important project, in the absence of specially allocated European funds (see http://www.essbilbao.com).

As a candidate host for the ESS, Bilbao depends exclusively on funds provided by the Spanish central government and the Basque government. These funds will provide sufficient core financial support to implement the project with a clear guarantee.