Maven dependency exclusion doesn't seem to work

I have a Maven project depending on couple other Maven projects. I am using Spring 3.1.1 in my project and dependent projects have 3.0.6. I am trying to exclude Spring 3.0.6 when deploying since having both isn't possible. I have added an explicit exclusion in my POM for that but for some reason I still see old version of spring core jars in the WEB-INF/lib folder when I start the Tomcat server. Can someone point me out where I am going wrong. Here is my pom.xml:

<project> .... <properties> <org.springframework-version>3.1.1.RELEASE</org.springframework-version> </properties> <dependency> <groupId>com.test.abc</groupId> <artifactId>abc</artifactId> <version>1.0</version> <type>war</type> <exclusions> <exclusion> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>${org.springframework-version}</version> <exclusions> <!-- Exclude Commons Logging in favor of SLF4j --> <exclusion> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>${org.springframework-version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>${org.springframework-version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-oxm</artifactId> <version>3.0.4.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> <version>${org.springframework-version}</version> </dependency> <dependency> <groupId>org.springframework.ws</groupId> <artifactId>spring-xml</artifactId> <version>1.0-m2</version> </dependency> .... </project>