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.

Intercepted missile debris damages kindergarten, clinic complex in Riyadh
Russian bomb kills 33 in street in east Ukraine stronghold
Canadian poet and writer Anne Carson wins 2026 Nobel Prize in Literature
One dead, two injured in Poland's second school attack in two days
French school blockades persist after PM's unspecified promises