How to open a url in a new window using SSRS 2008 reportviewer control

I need to open a web page in a new window as a link from a cell in an SSRS 2008 report. I found a reference on the web to say the best way to do this is to put in something like:

="javascript:void(window.open('"+ Fields!ReferURL.Value + "','_blank'))"

where the Fields!ReferURL.value is the page you want to navigate to in another window.

This works perfectly in report manager once the report has been deployed.

However, when we run the report from within a web page using the reportviewer control, the link does nothing at all.

Does anyone know how to get round this please?