Encroachement of property

I have a land of 35x170ft of a residential area in Tiruppur.It is bounded by my family members property on west and north sides and on the south by the third party while the eastern part is government land for about 20ft from the existing road. This property came to my power 5 years before. This third party has extended by keeping his old waste and woods on the south-east corner of my property into the government land and suddenly he constructed a compound wall around it by covering 20+ feets of my east facing side. i.e. govt land. when I enquired he said he has patta for that land. now after 3 years of constructing the wall I came to know he didn't have any rights to the property and he is lying to me since. now he is planting trees in this area and blocking the route from the road. He completely encroached the govt land and stating whoever can use govt land can keep them. how can I solve this issue and how can I approach govt officials regarding this issue. Do i need to pay compensation to remove his property