Over 11 Naam Tamizhar Iyakkam cadres were arrested here after they showed black flags and attempted to blockade the convoy of Sri Lankan Deputy Minister for Shipping and Aviation Services Dayasritha Tissera here on Thursday. The Deputy Minister along with his family had arrived here in the evening at the Shrine of Our Lady of Health to offer prayers. About 50 police personnel were stationed en route and at the Shrine premises to ensure safe passage to the Deputy Minister.