Police along with officials of the civic body, state pollution control board and CESC sealed 11 illegal tanneries in Tiljala, Topsia, Tangra and Karaya on Monday. The crackdown will continue till all the illegal tanneries have been sealed, said Ajey Ranade, the superintendent of South 24-Parganas police. Last week, the high court had ordered the state government to close down the illegal tanneries and file a compliance report by December 26. A special officer appointed by the court had put the number of illegal tanneries at 68.