Specification violation [EJB3 JPA 6.2.1.2] - You have not defined a non-jta-data-source for a RESOURCE_LOCAL

The same application that works fine in JBoss 4.2.2 fails in JBoss v5.0 with the following exception:

13:42:16,343 ERROR [AbstractKernelController] Error installing to Start: name=persistence.unit:unitName=#MyPU state=Create
java.lang.RuntimeException: Specification violation [EJB3 JPA 6.2.1.2] - You have not defined a non-jta-data-source for a RESOURCE_LOCAL enabled persistence context named: MyPU

The persistence unit for the application uses a datasource configured and managed by Spring.

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
<persistence-unit name="MyPU" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<properties>
<property name="hibernate.format_sql" value="true"/>
<property name="hibernate.order_updates" value="true"/>
<property name="hibernate.hbm2ddl.auto" value="validate"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.Oracle10gDialect"/>
<!-- property name="hibernate.transaction.factory_class" value="org.hibernate.transaction.JTATransactionFactory"/-->
<property name="hibernate.transaction.manager_lookup_class" value="org.hibernate.transaction.JBossTransactionManagerLookup"/>
</properties>
</persistence-unit>
</persistence>