In the modern computing era, access to resources is often restricted through contextual information and the attributes of users, objects and various other entities. Attribute-Based Access Control (ABAC) can capture those requirements as a policy, but it is not yet adopted like Role Based Access Control (RBAC) due to lack of a comprehensive administrative model. In the last few years, several efforts have been made to combine ABAC with RBAC, but they are limited to specification and enforcement only. Recently, we have presented a unified framework along with a role based administrative model that enables specification, enforcement and maintenance of unified access control policies, such as ABAC, RBAC and Meta-Policy Based Access Control (MPBAC). This paper describes role-based administrative model components and then present a methodology which uses a fixed-point based approach for verifying the security properties (like safety and liveness) of those policies in the presence of the administrative model. We also analyse the impact of ABAC, RBAC, MPBAC and administrative model components on the time taken for security analysis. Experimental results demonstrate that the proposed approach is scalable as well as effective.