Sri Lanka has temporarily banned the use of unmanned aircraft and drones following Easter Sunday bombings.
The country's Civil Aviation Authority (CAA) said it was taking the measure "in view of the existing security situation in the country".
Meanwhile, police forces continued to comb the Sri Lankan capital for possible clues to the attacks. Officers set off more controlled detonations of suspicious items, and stopped and searched vehicles.
So far, 76 people have been arrested with suspected terror links.
The father of two of the suspected bombers was detained on Thursday, with his house thoroughly inspected by officers.

Saudi Arabia intercepts and destroys drone in Mecca region
Six feared dead in helicopter crash in Indian Himalayan state, media report
Russia, Ukraine say aid is entering Oleshky, residents can leave if they wish
Four killed as Italian helicopter in EU mission in Bosnia crashes
