Addressing a programme in Ampara on Thursday, Wickremsinghe said the activities of the IS and the National Thowheed Jamath (NTJ) led by Zahran Hashim have been completely wiped out by now.
However, he cautioned that the terrorism may not end even if the whole NTJ is eliminated.
Wickremsinghe said when one group is eliminated, another group can be formed adding their purpose is to kill and die.
The Premier said new laws should be introduced to deal with any possible threats from such terrorist organizations as existing laws are not adequate.
The prime minister said the structure was created to face LTTE terrorism in the past but a new structure has to be put in place to eliminate ISIS terrorism.
He said the country should proceed with reconciliation among the people adding mistakes did in 1983 should not be repeated and no community in the country should be sidelined.
He asserted that all members of Zahran Hashim’s group, National Thowheed Jama’ath have either died, been killed or captured.
Wickremsinghe added that those who had links with the organization have also been arrested, while several others are to be arrested.