Service tax in case of sub-contractor

Dear Friends,

Facts:

Our client (Actual Service provider) is providing service to the Government agencies which are in the nature of Industrial or commercial construction service and residential complex service which are exempt from service Tax.

However in order to provide those service, our client has approached sub-contractor to provide the same. But the sub-contractor levies service tax on the amount of service provided by him.

Question:

Is there any circular or notification in force which exempt our client from paying service tax on the value of service received by him as input services ?

Also, if possibe please provide with the clarification on the above matter is no circuular or notification exists.

Thanks and regards

Manoj