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.

US military says it's completed 13th consecutive night of strikes on Iran
Indian government seeks time on minister resignation demand
Israel launches military operation after deadly clash near Palestinian village
Irish police intercept car with 'significant' bomb near Northern Ireland border
Spain declares national emergency over wildfires near Madrid and in Avila
