Security personnel stand guard outside St. Anthony's Shrine in Colombo Mohd Rasfan/AFP/Getty Images

An advisor to Sri Lanka’s President has told CNN that he believes one of the suicide bombers who detonated his explosives at the Shangri-La hotel in Colombo on Sunday was the ringleader.

Inshan Seelavan was the "mastermind" of the attacks, said the advisor, Shiral Lakthilaka. Other officials on Tuesday identified a radical extremist, Zahran Hashim, as a key figure in the attacks.

Lakthilaka, advisor to President Maithripala Sirisena, told CNN’s Ivan Watson the terrorists’ “entire network has been dispersed.” Other officials have warned that some suspects may still be at large.

"The most important thing is to look into the radicalization process," Lakthilaka said.

Lakthilaka also confirmed the President asked for the resignation of the one of the country's defense ministers, Hemasiri Fernando, and the country's police chief, Pujith Jayasundara. He added that constitutionally the president doesn’t have the authority to dismiss the police chief.