Militants were targeting five locations for attacks on Sunday and today, security officials have revealed.
One of them was Batticaloa, a city on the east coast where 27 people were killed in a church blast.
A top police chief disclosed: “There could be another wave of attacks.
“The relevant information further notes that persons dressed in military uniforms and using a van could be involved in the attacks.”
Scores of suspected Islamic extremists have been arrested since the Easter weekend slaughter, which killed over 250 people.
Authorities have implicated two terrorist groups, National Thawheedh Jamaath (NTJ) and Jammiyathul Millathu Ibrahim (JMI), but ISIS has also claimed responsibility.
Intelligence officials believe NTJ and JMI would have required help from international terror networks to carry out such a co-ordinated and devastating attack.
Sri Lanka’s Prime Minister Ranil Wickremesinghe last week said ISIS may be linked to the blasts.
He told reporters: “This could not just have been done locally.
“Persons dressed in military uniforms and using a van could be involved”
“There had been training given and a co-ordination which we are not seeing earlier.”
The government last night lifted a curfew for the first time since the bombings, but police are still conducting random body checks and churches in the capital Colombo.
Sri Lanka has also issued a ban on all types of burqas and veils that cover the face.
A statement from the President’s office read: “President Maithripala Sirisena took this decision to further support the ongoing security and help the armed forces to easily identify the identity of any wanted perpetrators.”