had to change label module:

diff --git a/openerp/addons_extra/label/label_report_engine.py b/openerp/addons_extra/label/label_report_engine.py
index b1419d6..edce844 100644
--- a/openerp/addons_extra/label/label_report_engine.py
+++ b/openerp/addons_extra/label/label_report_engine.py
@@ -211,7 +211,11 @@ class report_label_xsl(report_rml):
                 if text_line: # Line that includes text o fields to print
                     rline = re.sub(r'(<([\w/]+)\s*[^>]*>)', r'</xsl:text>\1<xsl:text>', line) # To put <...> report tags outside <xsl:text>...</xsl:text>
                     rline = re.sub(r'\$\{([\w\.]+)\s*[^}]*\}', r'</xsl:text><xsl:value-of select="\1"/><xsl:text>', rline)
-                    rline = '    <para style="nospace"><xsl:text>%s</xsl:text></para>\n' % rline
+                    # barCode expects it's value without <para> tags
+                    if re.search(r'object\.ean13', line):
+                        rline = '<xsl:text>%s</xsl:text>\n' % rline
+                    else:
+                        rline = '    <para style="nospace"><xsl:text>%s</xsl:text></para>\n' % rline
                     tline = re.sub(r'(<[^>]*>)', '', line) # To exclude <...> tags
                     tline = re.sub(r'(\$\{([\w\.]+)\s*[^}]*\})', r'<\2>\1</\2>', tline)
                 else: # Line that only includes report tags like <tr>, <td>, <blockTable>, <nextFrame/>, ... to control the report format

and use barCode like in the 3rd example

<barcode x="1cm" y="1cm" height="1cm" code="EAN13">
${object.ean13}
</barcode>

do not insert spaces at the beginning of lines

Is the Label module module available on V.7?