In a letter to the Northern province chief minister, C V Wigneswaran, Mr Sritharan called for immediate action to the stop the occupation.
The land is situated by the Neththili river in Kilinochchi, by the main road connecting Paranthan to Mullaitivu.
A copy of the letter was also sent to the provincial education minister, Mr Gurukularajah, the district secretaries for Kilinochchi and Kandavali, and the Grama Nilayadari of Tharumapuram.