Set soapui.properties in pom.xml from an external file

Initial I'm using the following content in my pom.xml:

(...)
<configuration>
<projectFile>${soapui.project.name}.xml/projectFile>
<projectProperties>
<value>{$variable1}</value>
<value>{$variable2}</value>
</projectProperties>
</configuration>
(...)

But, since i need to run this test in several environments, I'm trying to load an external file (variable_file.properties), with the following content:

variable1=value
variable2=value

And change my current pom.xml with the following content:

(...)
<configuration>
<soapuiProperties>
<property>
<name>soapui.properties</name>
<value>variable_file.properties</value>
</property>
</soapuiProperties>
</configuration>
(...)

Unfortunately, with this approach, I can't load the external file in order to use the variables.

Anyone can give any idea why this approach doesn't work, i'm currently using maven3.

or there is a better solution?

Thanks, delpier