extra margins around eternal-graphic

Hi,
I try to have a svg graphic on all the page in a PDF. I use FOP 1.1.
I test this FO file, but I have always green left and right margins 
(background color of external-graphic) and a red on the bottom of the page.
The SVG file isn't extend until the total size of defined page.
I put the font-size=0 and line-heigth=0
I really don't have idea I try to put margin and padding to 0 but it 
doesn't change anything.
Marc

Here is my FO file :
<?xml version="1.0" encoding="UTF-8"?>
<fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format">
    <fo:layout-master-set>
       <fo:simple-page-master master-name="page" margin-bottom="0" 
margin-left="0" margin-right="0" margin-top="0" page-height="244cm" 
page-width="164cm">
          <fo:region-body margin-bottom="0cm" margin-left="0cm" 
margin-right="0cm" margin-top="0cm"/>
       </fo:simple-page-master>
    </fo:layout-master-set>
    <fo:page-sequence master-reference="page">
       <fo:flow flow-name="xsl-region-body">
          <fo:block-container left="0" top="0" height="244cm" 
width="164cm" background-color="red" font-size="0" line-height="0" 
margin-left="0" margin-right="0">
             <fo:block background-color="blue" font-size="0" 
line-height="0" margin-left="0" margin-right="0">
                <fo:external-graphic src="../exemple/dibon2-3-4.svg" 
content-height="244cm" content-width="164cm" font-size="0" 
line-height="0" background-color="green" padding-left="0" 
padding-right="0"/>
             </fo:block>
          </fo:block-container>
       </fo:flow>
    </fo:page-sequence>
</fo:root>