regular expression issue in XSLT 2.0

In this snippet
<xsl:template match="test[matches(.,'(.*)\{\$gemeente\}')]">
        <xsl:analyze-string select="." regex="(.*)\{\$gemeente\}">
           <xsl:matching-substring>Blah</xsl:matching-substring>
       </xsl:analyze-string>
</xsl:template>

The regular expression ((.*)\{\$gemeente\})is accepted within the
matches() function.
However an error is thrown (both in Saxon 8SA and XML Spy) on the same
regular expression within the attribute regex of xsl:analyze-string.
I suppose this has to do with the fact that the regex attribute value
acts as an attribute value template, where the {} braces have specific
semantics.

So
{} meaning attribute value template
{{ }} meaning regex occurrence indicator

But how do you escape then the curly sign as a character?

Regards,


Paul