An outstanding security problem in mobile agent systems is resource access control, or authorization in its broader sense. In this paper we present an authorization framework for mobile agents. The system takes as a base distributed RBAC policies allowing the discretionary delegation of authorizations. A solution is provided to assign authorizations to mobile agents in a safe manner. Mobile agents do not need to carry sensitive information such as private keys nor they have to perform sensitive cryptographic operations. The proposed framework makes extensive use of security standards, introducing XACML and SAML in mobile agent system. These are widely accepted standards currently used in Web Services and Grid.