Using antcontrib <if> task via maven-antrun-plugin

My maven java project uses the maven-antrun-plugin to execute a deploy.xml ant script that deploys my app. The deploy.xml uses the <if> task and this seems to be causing the problem;

[INFO] Executing tasks
[taskdef] Could not load definitions from resource net/sf/antcontrib/antlib.xml. It could not be found.

deploy:
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] An Ant BuildException has occured: The following error occurred while executing this line:
E:\My_Workspace\xxxxxx\xxxxxx\xxxxxxx\deploy.xml:24: Problem: failed to create task or type if
Cause: The name is undefined.
Action: Check the spelling.
Action: Check that any custom tasks/types have been declared.
Action: Check that any <presetdef>/<macrodef> declarations have taken place.

Here is the antrun plugin config from my pom;

<plugin>
    <inherited>false</inherited>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-antrun-plugin</artifactId>
    <executions>
        <execution>
            <id>remote-deploy</id>
            <phase>install</phase>
            <configuration>
                <tasks>
                    <taskdef resource="net/sf/antcontrib/antcontrib.properties" classpathref="maven.plugin.classpath"/>

                        <property name="compile_classpath" refid="maven.compile.classpath" />
                        <property name="runtime_classpath" refid="maven.runtime.classpath" />
                        <property name="plugin_classpath" refid="maven.plugin.classpath" />