The police authorities on Thursday publicly released images of wanted people in connection to the Easter Sunday bombings.
They are seeking the assistance of the general public to apprehend the suspects in questions.
Police have released the images and names of six suspects including three females. The public is requested to provide any credible information regarding the suspects to the Criminal Investigations Department (CID).
Thousands of additional police and troops have been deployed across the country in the hunt for at least four men and a woman believed linked to the attack who remain at large.
Sixteen people were arrested overnight in a series of raids and police said about 75 people were now in custody undergoing interrogation in relation to the attack that killed 253 in coordinated bombings of three churches and three luxury hotels.
Police initially released images of two women and four men, saying they were wanted in connection with the attacks – but were later forced to apologise when it emerged one of the images was of US-based activist Amara Majeed.
Sri Lankan Army Brigadier Sumith Atapattu said the army increased its deployment on the streets by 1,300 to 6,300, with the navy and air force also deploying 2,000 more personnel.
“We are armed with powers to search, seize, arrest and detain under emergency regulations,” he said. “We are involved in static guard duties, patrolling and helping with cordon-and-search operations.” The government also announced a ban on all drone flights and said licences issued to all commercial operators were suspended with immediate effect.