Stamp duty and registration

when the Government is leasing property (or giving licence to enter the property)  for more than two years to a Registered Society is the property liable for stamp duty and should the property  be registered.  My question is whether contracts on documents in which Government is a party is liable for stamp duty and registration.  Alternately, whether Government is exempt from stamp duty and Registration under the Indian Stamp Act?  What is the position of the state laws