Unable to locate Spring NamespaceHandler for XML schema namespace [http://www.springframework.org/schema/security]

I am developing my first application in spring security. My applicationContext-security.xml file looks like this:

<?xml version="1.0" encoding="UTF-8"?>

<!--
  -  Namespace-based OpenID configuration
  -->

<b:beans xmlns="http://www.springframework.org/schema/security"
    xmlns:b="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
                        http://www.springframework.org/schema/security http://www.springframework.org/schema/security/spring-security-3.0.xsd">

    <http>
        <intercept-url pattern="/**" access="ROLE_USER"/>
        <intercept-url pattern="/index.xhtml*" filters="none"/>
        <logout/>
        <openid-login login-page="/index.xhtml" authentication-failure-url="/index.xhtml?login_error=true">
            <attribute-exchange>
                <openid-attribute name="email" type="http://schema.openid.net/contact/email" required="true" count="2"/>
                <openid-attribute name="name" type="http://schema.openid.net/namePerson/friendly" />
            </attribute-exchange>
        </openid-login>
        <remember-me token-repository-ref="tokenRepo"/>
    </http>

    <b:bean id="tokenRepo"
            class="org.springframework.security.web.authentication.rememberme.InMemoryTokenRepositoryImpl" />

    <authentication-manager alias="authenticationManager"/>

    <user-service id="userService">
        <user name="http://user.myopenid.com/" authorities="ROLE_SUPERVISOR,ROLE_USER" />
    </user-service>

</b:beans>

and Web.xml file is:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
  xmlns:xsi="http://www.w3.org/2001/XML