Labels and place-holders in form inputs

I have an application that uses “placeholder” text inside a forms input field to tell the user what is required. This helps the form to be displayed well on a small screen such as a mobile phone. However I still need to include the <label> element (hidden via CSS) to comply with WCAG and ensure that *all* screen reader users can always know what is required.  My problem is that some screen-readers read both the <label> and the placeholder.
Any suggestions or comments warmly welcomes
Richard
www.userite.com