Demolition of House by Panchayat

Dear Sir/Madam, My house is built with brick wall of 5 inch width and roof is covered by asbestors filled up with concrete of 3 inch depth over it in my village. Total land is of 8 satak and covered area by the construction is 4 satak. This construction is completed in year 2011. Prior to this construction my elder brother had been asked by panchayat to show the letter from myself stating that myself has no objection to built the house in my father (Expired) land (Bastu). That time they also verbally told there is no need of taking formal permission of construction of house since one letter has been issued. Therefore, during construction of building no objection came from the panchyat. Now the ruler of panchayat has been changed and new ruler asking for building permission and threatening of demolition of house. So at this point I wanted to know the following information: 1) Can I be defaulter of making such type of building? 2) If yes, which are the steps panchayat may take? 2) After almost four and half years, can Panchyat demolish my house? If yes, then in which ground they can do so? Please help me. With thanks and regards, P.S.