Taxes on shares


My uncle bought few shares of Indian oil India in my father's name about 25 some years ago without telling us. We came to know now when my uncle had asked my father for his PAN number and he denied giving it. My uncle said okay. I think he may sell the shares in denominations smaller than 20,000 and reap the benefits without dealing with the PAN card issue? What about the taxes? Who will be liable for the taxes involved?
My father had not spent a single dime on buying those shares and had not even given his consent. What are all the legal actions that we can follow to make sure that tax liability from income of those shares falls on my uncle? Awaiting suggestions from experts.